Paternal Age and Homosexuality

There’s something interesting about the paternal age effect in homosexuality – apparently there isn’t one. It certainly exists for autism, schizophrenia, manic-depression, and mental retardation, which suggests that de novo mutations play an important role in all of them. But homosexuality, although it is obviously a Darwinian mental illness – despite the opinions of the loons who wrote the DSM – does not seem to be mutation-driven. At least not much. It’s a different kind of crazy.

There were already reasons to think this. First, homosexuality is A. common and B. involves disruption of a relatively simple adaptation, one that ought to present a smallish mutational target. It would not be easy for something driven by mutation to become that common (> 1%), when the number of key genes involved in sexual targeting probably is not especially large. Certainly not large compared to the number that influence general intelligence.

Besides that, we (I have a tapeworm) don’t see syndromic forms of homosexuality, ones in which particular mutations cause the phenotype of interest (deafness, for example) but also cause other characteristic changes, such as wide-set eyes and a white streak of hair (Waardenburg syndrome). About 15% of the mutations causing deafness are syndromic. I don’t know the fraction of mutations causing mental retardation that are syndromic, but it must be substantial: that’s why people working with mentally retarded youth talk about FLKs – funny-looking kids. There might be genetic/syndromic kinds of homosexuality, but they must be rare. They might be very informative, however.

By the way, I’m supposed to say ‘intellectual disability”, instead of retardation, according to various morons.

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118 Responses to Paternal Age and Homosexuality

  1. jb says:

    I’ve always been puzzled by how humans manage to form sexual preferences at all, including normal heterosexual preferences. With most mammals sexual attraction is governed by the sense of smell (or pheromones — same thing?). That’s very deeply rooted, and easy to understand. But that’s not how it works for humans, who don’t have much of a sense of smell.

    So how does it work with people? Primates are visual creatures, so maybe it’s a visual thing? Men and women are shaped a bit differently, but there is a lot of variation, and the differences really aren’t that huge. Does sexuality work differently among people who have been blind from birth? I’m not aware that it does, but let me know if I’m wrong.

    But if people aren’t attracted by the smell of the their preferred sex partners, or by the shape (hourglass, triangle, etc.) , then what?

    • erica says:

      You might find interesting the work of Catherine Dulac who researches olfactory signaling and pheromones.

      They established by knocking out vno receptors that, at least in the mouse, the vomeronasal organ is responsible for aggression and also for gender discrimination, not the olfactory system, which is responsible for mating. Further, they found that circuitry for male behaviors exist in the female but that those behaviors are repressed by the vno.

      While we don’t know what sensory mechanism is at work in mate identification in humans as we do in mice, whatever is at work also affects aggression, for not only do male homosexuals choose an inappropriate mate, they also lack the aggression of heterosexual males and do so from an early age. Even in cases of the non-effeminate gay male, it’s common to note, for example, a softer or gentler voice, even though those voices may be masculine in resonance.

      If she worked with sheep and not mice, Ms. Dulac might get us somewhere a bit faster. 🙂

  2. gcochran9 says:

    There is a widespread suspicion that psychotherapists are crazier than average, but I don’t know if it is really so. I suspect that the people writing the DSM don’t know much about evolutionary biology or genetics. I think that they don’t routinely analyze disease syndromes by considering their prevalence and their likely impact on fitness in the past. Because they don’t have a real theory, their classification scheme does not carve nature at a joint.

    So, they can call an adaptive function pathological and a serious Darwinian disease normal. And that’s insane!

    • Starsky says:

      “the people writing the DSM don’t know much about evolutionary biology or genetics”

      We can finally agree on something!

    • TWS says:

      which adaptive function?

    • jaroto says:

      Did you ever visit the website (before they took down the diagnoses in preparation for the DSM-5 release)? They took an empirical approach, for example clustering disorders that evidence did not suggest were distinct and creating new disorders from a single disorder that evidence suggested was too heterogeneous. The most prominent example of this is Autism/Aspergers merging together, but they did the same thing for alcohol abuse and alcohol dependence (there was no evidence for two separate hierarchical disorders, but rather evidence suggested this disorder and its symptoms was on a single continuum).

      The empirical evidence they considered, however, probably did not include much from evolutionary biology (you’re right). I’m not suggesting the DSM-5 is good, or even better than the DSM-IV, but they use evidence from studies that has analyzed disease syndromes (just not evidence from your field).

      If anything, I think it just speaks to the fact that society (i.e., treatment receivers) and medical professionals (i.e., treatment providers) do not consider one’s ability to pass their genes on as a mark of stability, well-being, or happiness, regardless of whether it’s because that person is heterosexual (and doesn’t want kids) or homosexual.

    • Laban says:

      “There is a widespread suspicion that psychotherapists are crazier than average, but I don’t know if it is really so.”

      My wife (a nurse) says that nurses working in mental health have a higher proportion of ‘issues’.

    • Abelard Lindsey says:

      Its actually much worse than that. Psychiatry is not a legitimate science-based discipline, with diagnosis of mental health being based on the understanding of the underlying molecular biology. None of the defined conditions co-relate with any underlying etiology. Also, you can take a patient to a clinic and get one diagnosis, take the patient in again 6 months later and get a completely different diagnosis.

      Until some molecular biology basis of neuro biology gets understood and can be used as the basis of psychiatry, psychiatry should be considered with healthy skepticism (e.g. it is nothing more than “voodoo” pseudo-science)>

    • Phil Adley says:

      I suspect that the people writing the DSM don’t know much about evolutionary biology or genetics… Because they don’t have a real theory, their classification scheme does not carve nature at a joint… So, they can call an adaptive function pathological and a serious Darwinian disease normal. And that’s insane!

      LOL reminds me of Blanchard on hebephilia.

  3. soren says:

    Here’s a deleted blog post OKCupid took down showing that men outside women’s typical height preference(5’8″-ish to 6’4″-ish) are more likely to identify as homosexual.

    Original chart is here…

    • That Guy says:


      That’s fascinating!

      I remembering decades years ago that having an extra Y-Chromosome inclines XYY men to be:
      1. Extra tall
      2. Extra aggressive/prone to violence
      3. Have moderate to severe acne
      4. Homosexual

      So maybe some loci on the Y-Chromosome are in some kind of harmony with some loci on the X-Chromosome, and the extra Y throws that off, as it produces an unmatched Y locus, which acts up?! 😉

  4. georgesdelatour says:

    “Darwinian mental illness” – intriguing phrase. What’s the difference between Darwinian metal illness and mental illness? What about a heterosexual serial rapist? Does he have Darwinian mental wellness, because he’s more likely to pass on his genes than the gay person is?

    • Starsky says:

      Excellent point.

      • georgesdelatour says:


        It’s one thing to notice that a trait militates against fecundity. It doesn’t follow that it’s therefore an illness.

        I have several friends – heterosexual couples, including my brother and his wife – who have chosen to be childless. They may be missing out on something wonderful. But they’re not mentally ill, the way someone with schizophrenia is.

        • gcochran9 says:

          Vulnerability to something environmentally new is not surprising. Falling for a Blade-Runner style replicant would be maladaptive, but it wouldn’t be an evolutionary anomaly. A strategy that always worked before (chasing anyone who looks like Sean Young) fails in a tricky new environment.

          On the other hand, disinterest in the opposite sex has always been a losing strategy. It should be very rare. But it’s not. High frequency, way higher than you’d expect from mutational pressure, of something that would never have worked, is a puzzle.

          I once told Henry he should put this question on an exam. Evidently it would have a been a toughie.

          Understood properly, reduction in fitness is THE prime indicator of a Darwinian disease state. Salmon die as a consequence of their method of reproduction. That’s not a Darwinian disease – but failure to try to ascend that river would be.

          • jaroto says:

            So vulnerability to something new is maladaptive, as is openness to experience???

            Putting aside my confusion, I don’t know if there are data to back up this statement, but it seems that in more conservative parts of the country a vulnerability to something new is precisely what leads individuals having kids in large heaps (i.e., having a family rather than getting a college education and a well-paying job).

    • jaroto says:

      Agreed. Mental illness should be defined by one’s ability to make good decisions (e.g., get out of bed, get to work, be productive at work, lead a stable life), and I’m not aware of any evidence that suggests homosexuals are less successful (e.g., in terms of employment, income, etc.).

      Also, the DSM is intended to help clinicians provide treatment for mental illnesses, and you’d be hard-pressed to find a legitimate health care provider who will attempt to treat homosexuality as a mental illness.

      • jaroto says:

        *meant to suggest that vocational success ias an indicator of mental stability (not suggesting that it defines mental stability).

      • JayMan says:

        Of course, by your definition, a “mental illness” is a trait or a set of traits that are not necessarily evolutionarily maladaptive, either today or in the past, just not socially acceptable/desirable.

        On the flip side, Dr. Cochran’s definition of Darwinian mental illness would now include modern liberalism and/or the entire Big Five personality characteristic “openness to experience,” which are, in modern times, quite maladaptive.

        • gcochran9 says:

          There are lots of behavior patterns that were adaptive in the past but aren’t today. Liking sweet foods used to be adaptive, but saccharin fools you. If the world changes enough, anything can become maladaptive. The most interesting kinds of crazy are those which never would have worked.

      • gcochran9 says:

        That definition doesn’t provide any insight as to cause. Thinking about fitness does.

        Also, by that criterion, anything that causes sterility is harmless, as long as you still make it to work. Biologically, that’s silly.

      • erica says:

        “and you’d be hard-pressed to find a legitimate health care provider who will attempt to treat homosexuality as a mental illness.”

        Sure, but that’s because such providers have never been successful in treating it, that is, in making a gay person straight. There is no effective treatment, no way to reverse orientation. Imagine what might happen if suddenly a treatment existed that actually worked, a magic pill of sorts that turned a male’s attractions from members of his own sex to members of the opposite sex or one that prevented little boys from wanting to dress up in mommy’s heels and clothes, that made him enjoy rough housing it with his little friends and Dad rather than sitting in the corner watching or retreating altogether.

        Imagine if Cochran is right about it probably being the side effect of a pathogen. Don’t you think that people would suddenly want their kids innoculated against that pathogen?

        Of course, I won’t go so far as to say that if that were to happen the term “mental illness” would suddenly find favor. No, that’s a bridge too far. They’d come up with another term.

        • gcochran9 says:

          Not knowing how is a logical reason for not attempting to treat homosexuality, but I doubt if it is the actual reason. Physicians have spent millennia treating syndromes they couldn’t cure – as long as the marks kept paying, why not?

      • Peter says:

        What are “good decisions”? It seems that unless they’re ultimately defined in terms of fitness, “good decisions” can be whatever you want. Same goes for “health” and “illness”. Sure, getting out of bed everyday and going to work enthusiastically can seem healthy, but it can also seem pointless and crazy, like voluntary slavery, if it isn’t toward sustaining offspring.

    • gcochran9 says:

      I doubt if that behavior had high fitness in past environments, because most environments required two parents to successfully raise a child. Second, rapists didn’t have long careers, because traditional societies didn’t have much anonymity.

      But it works in some situations. Ducks do it, and it’s not because they’re crazy. If your general argument is that unpleasant behaviors can be adaptive and thus not crazy – sure.

      • jaroto says:

        Going with your definition of mental illness, isn’t being homosexual becoming progressively less maladaptive with the ability of homosexual couples to have their own children through various alternative means?

        That is, the reproductive fitness of homosexuals must be increasing.

        • gcochran9 says:

          I’m sure that that on average they still have low fitness. Anyhow, it’s irrelevant. If we’re trying to understand what causes homosexuality, you need to think about its impact on fitness in the past. Why isn’t homosexuality really rare? At least as rare as genetic deafness, < 1 in 1500? Sure, aliens from Tau Ceti may someday show up and start industrial-scale cloning of gay men, but that wouldn’t explain why they’re moderately common today, would it?

          By the way, most of those clones would be heterosexual, judging from the observed MZ twin concordance.

      • jaroto says:

        *their own biological children.

      • JayMan says:


        “Going with your definition of mental illness, isn’t being homosexual becoming progressively less maladaptive with the ability of homosexual couples to have their own children through various alternative means?

        That is, the reproductive fitness of homosexuals must be increasing.”

        Probably not (though this includes bisexual men as well as true homosexuals).

      • TWS says:

        Canoe weddings and bride stealing include rape in the beginning at least. Eventually the women function mostly normally within their new group. Primitives do it all the time even today.

        Slaves cannot say ‘no’. For some men institutionalized rape via slavery was very successful. Aren’t some of the Saudi princes children of slaves?

      • Anthony says:

        Powerful men in pre-modern societies would often act in ways which would get them jailed in our society. Even though power increases one’s attractiveness to women, it also means, in most times and places, you don’t need to worry so much about consent.

        Acquiescence to this behavior has survival advantages for the woman and her offspring, especially in societies where power is hereditary.

    • Greying Wanderer says:

      “What about a heterosexual serial rapist? Does he have Darwinian mental wellness, because he’s more likely to pass on his genes than the gay person is?”

      In the Congo yes – if you watch the documentaries you’ll see whole villages where half the children are the product of militia rapes.

      Other places, no.

      I think rape is an r-type reproductive bahaviour which has been largely suppressed in K-type populations.

  5. Steve Sailer says:

    The one syndrome associated with male homosexuality appears to be a lisp (not a lithp, but a lisssssp — see “The Producers” for an exaggerated version) found in some not huge but not insignificant fraction of gay men.

  6. JayMan says:

    There is the “gay face“, which is in the same vein as “funny looking kids.”

    • gcochran9 says:

      Not quite. It’s the same, more or less, in different gay men. Funny looking kids come in many flavors – fragile-X kids don’t look the same as those with Down syndrome, etc.

  7. Starsky says:

    “a Darwinian mental illness”

    Only if you’re still ignoring group selection.

    • gcochran9 says:

      The problem is, I understand group selection. Selection at the individual level is almost always more powerful, nor is there any plausible way in which homosexuality would materially aid group success.

    • Peter says:

      What would be the groups? Who, what, where is the germline?

      I remember reading Edward O. Wilson and he seemed to suggest – I’m not sure if he said it explicitly – that the group selection among insects could be viewed as individual selection among the queens.

      • Jerome says:

        If only the queens can reproduce, then by definition, selection is among them as individuals. But it probably makes more sense to regard the queens as the reproductive organs of an animal called a “hive”. Just as you are a hive of cells. It happens that the hive is not physically connected, as your body is. But individuals cut off from the hive quickly die, just as your cells would.

  8. Jason Malloy says:

    “There’s something interesting about the paternal age effect in homosexuality – apparently there isn’t one.”

    Are there papers that have tested this directly? Blanchard and Bogaert estimate that almost one in three cases of male homosexuality are linked to the fraternal birth order effect. My impression from the literature though, is that nearly as many of these gay birth order studies show a sororal effect too. Either way, all these older siblings would seem to indicate that gay men have older parents.

    • JayMan says:

      I’m not so sure that these studies have established that this effect isn’t entirely a statistical artifact (homosexuality, being a rare trait, is more likely to show up in larger sibships).

    • Jason Malloy says:

      OK, my impression from the literature was correct, but wrong. Gay men do have more older sisters, but that’s a consequence of having more older brothers. Blanchard teases this out with logistic regression in his meta-analysis. He also notes: “The relation between number of older brothers and male homosexuality is not an artifact of higher maternal or paternal age (Blanchard and Bogaert, 1996a, b, 1997a, 1998; Blanchard and Sheridan, 1992; Bogaert et al., 1997)” (p. 176)

      @ Jayman. Blanchard also finds that gay and straight sibling number are virtually identical (2.61 gay vs. 2.70 straight). Gay men don’t come from larger families, they’re just disproportionate among later born.

      • erica says:

        Here’s a more recent study from Andrew Francis of Emory (2008) on the older brother hypothesis which does not find the effect: “Family and Sexual Orientation: The Family-Demographic Correlates of Homosexuality in Men and Women”

        Abstract : “Using a nationally representative sample of young adults, I identify the family-demographic correlates of sexual orientation in men and women. Hence, I test the maternal immune hypothesis, which posits that the only biodemographic correlate of male homosexuality is the number of older brothers, and there are no biodemographic correlates of female homosexuality. For men, I find that having one older brother does not raise the likelihood of homosexuality. Although having multiple older brothers has a positive coefficient, it is not significant. Moreover, having any older sisters lowers the likelihood of homosexual or bisexual identity. For women, I find that having an older brother or having any sisters decreases the likelihood of homosexuality. Family structure, ethnicity, and education are also significantly correlated with male and female sexual orientation. Therefore, the maternal immune hypothesis cannot explain the entire pattern of family-demographic correlates. The findings are consistent with either biological or social theories of sexual orientation.”

        About the sample:

        “I use the National Longitudinal Study of Adolescent Health (Add Health), a nationally representative study of adolescent health in the United States (Udry, 2003). Adolescents in grades 7 through 12 were initially interviewed in 1995 and 1996 (Waves I and II) and were reinterviewed in 2001 (Wave III). The sample size of male respondents is about 5,000, and the sample size of female respondents is about 5,600. Table 1 displays summary statistics. At Wave III, all respondents in the sample were 18 years old or older. About 88% were between the ages of 20 and 24.”

        Assessment item:
        ” ‘Choose the description that best fits how you think about yourself: 100% heterosexual; mostly heterosexual, but somewhat attracted to people of your own sex; bisexual, that is, attracted to men and women equally; mostly homosexual, but somewhat attracted to people of the opposite sex; or 100% homosexual. ‘ ’’

        I am not competent to assess his methodology. Just thought I’d toss this out.

  9. dearieme says:

    I remember reading that fraternal birth order effects almost entirely vanished if you classified only children not as first born but as last born.

  10. erica says:

    “Not knowing how is a logical reason for not attempting to treat homosexuality, but I doubt if it is the actual reason.”

    Haven’t many actually attempted to treat it with a variety of methods throughout the years: electroshock therapy, psychotherapy, Pavlovian-based therapy, and for those who today swim against the tide, something called “reparative therapy” (just more Freudian nonsense), etc.?

    Of course, I get your point. It’s not pc to try anything that might change what a lot of activism has managed to term a “normal state.”

    I think the activists kind of lucked into this. For years they worked to convince people that homosexuals didn’t simply choose to be attracted to men and choose not to be attracted to women any more than heterosexuals chose their attractions. When finally they rightfully had some success with their arguments, they saw the opportunity to go a step futher with terminology–argue that since homosexuality has a biological origin, it is “natural” because it’s not chosen.

    Now, they go a step even further by arguing that it’s not maladaptive, throwing out the gay uncle and worker bee stuff.

    That brings up something I’ve been meaning to ask you, Dr. Cochran. Researchers in the this field call homosexuality “naturally occurring.”

    As a non-scientist, I understand that no matter what causes it, it’s not a choice, that even if a pathogen causes it directly or indirectly or if intrauterine hormonization effects cause it, it’s the result of biological processes over which an individual has no control so in thit way “naturally occuring” makes sense.

    On the other hand, I wondered if this phrase is the researcher’s way of being pc while not wholly scientifically inaccurate or if the term is scientifically inaccurate in a Darwinian sense.

    Could you clarify that?

    • JS says:

      “Naturally occurring” can mean just about anything that occurs in nature. Bestiality is “natural” in this sense. The more interesting use of “natural” or “normal” is like “in accord with design” or “was selected for by natural selection.”

  11. JS says:

    Seems to me that at some point after the sex of a fertilized egg is determined nature must see to it that a process kicks off with the function to make sure that the object of sexual attraction be the opposite sex. One cause of homosexuality (there probably are multiple causes), would be this process either failing to kick off or malfunctioning and hooking up the subject with the wrong object. Everything in the biological world with a function can and does malfunction, so we should expect to find those who have a malfunctioning sexuality. For some reason though we still feel that in the case of sexual attraction (and nowhere else), subjective certainty implies infallibility.

  12. Juan Valdez says:

    In the past, homosexual orientation was not fitness reducing in most human population groups, because the homosexual identity had not yet been invented.

    People who would be classified as homosexuals today would have behaved as heterosexuals or bisexuals back then. They’d marry and have children as normal, because it was socially expected and because it was economically beneficial. They might enjoy some homosexual activity on the side, but that would only be harmful to fitness if it lead to some kind of STD or lynching. A certain openness to this sort of activity might be helpful for stress release or bonding or dominance or something. Certainly prisoners and sailors on ships at sea seem to enjoy it, even when they don’t identify as homosexuals.

    Some hunter gatherer societies like the Aka pygmies literally have no concept of homosexuality. They’ve never heard of it and they don’t understand it easily when you try to explain it to them. People may in these groups may be born with a certain level of openness to the possibility of homosexual activity, but they will find it nearly impossible to articulate this interest or find anyone with similar desires. So the desire goes unexpressed and they marry and father children, just like the people who were born without an openness to the possibility of homosexual activity.

    People are exclusively homosexual in the modern era because a) we’ve invented a homosexual identity b) social expectations have broken down c) attitudes have changed to the point where few people care about having children anymore d) our lives are pretty empty and adopting an “identity” or “lifestyle” gives us something to care about.

    Homosexuality never got selected out of the population for the same reason that sexual interest in the Furry Fandom never got selected out of the population. It’s simply a matter of crazy modern people latching onto a minor personality quirk and turning it into an identity. Of course, now that they’ve done so, it probably is starting to get selected out of the population.

    • gcochran9 says:

      In the same sense, in the past, people who didn’t get hungry were no more likely to starve to death than those who did. I’ve heard it before, and it didn’t make any sense the first time.

      • Juan Valdez says:

        You’re making the mistake of buying into the modern frame of homosexuality as an exclusive orientation, the reverse of heterosexuality. Yet as Foucault pointed out, prior to the 19th century, homosexuality was not seen this way. Sodomy was simply a criminal act, not evidence of some fundamental sexual identity.

        Once you reject the modern frame, things start to make more sense.

        Homosexuality as a fundamental identity that prevents you from trying to reproduce, that’s clearly fitness reducing.

        But homosexuality as an openness to a certain kind of leisure activity? That’s not so clearly fitness reducing. At least, not until modern society comes along and allows people to turn every leisure activity into a lifestyle.

        • gcochran9 says:

          I am reminded of when people said how there would be lots of AIDs transmission by bisexual men.

          Didn’t happen. I don’t buy into frames: I count corpses. And babies.

      • jb says:

        Greg, I don’t understand your objection to Juan’s point. He is saying that, because of social expectations, until fairly recently homosexual men did have babies. That seems reasonable enough to me.

        I don’t even see much reason to think they would have had that many fewer babies than heterosexual men. The number of children a man can have is limited by his wives’ ability to bear children — once a year at most — not his appetite for sex. Unless a man is utterly incapable of having sex with a woman, he should be able to impregnate her over the course of a year. (He’s going to know the procedure, and is going to want babies for the same social reasons as everybody else).

        Of course homosexual men would be less inclined to play the field and impregnate other men’s wives, so I suppose that may be a modest selective disadvantage. But that’s a dangerous game anyway in a small hunter-gatherer society, where there is little privacy, and people tend to be good trackers.

        And of course I’m only talking about men here. For gay women it wouldn’t even have been an issue — they would have been married off and had babies just as routinely as straight women.

        So anyway, can you let us know exactly why you believe pre-modern homosexuals had significantly fewer babies than heterosexuals?

        • gcochran9 says:

          Historically, something like half of guys didn’t reproduce at all. You had to compete. You may think uninterested men would have done nearly as well, but that’s silly.

          Next, this isn’t horseshoes: close doesn’t count. If homosexuality depressed average reproduction by as little as 10%, you’d expect it to be far rarer than it is.

    • nameless37 says:

      It’s a good theory but I think it’s wrong.

      You don’t need an acceptance of homosexual identity for homosexuality to be maladaptive. Exclusive homosexuals have little to no sexual attraction to persons of opposite sex. (Yes, it’s been actually measured in the lab, they have significantly different arousal responses to homosexual and heterosexual stimuli.) That by itself will guarantee that they will have fewer children even if they get married because social norms dictate that. In many primitive societies, having children is not economically beneficial. Children just “happen” because males are naturally attracted to females and vice versa. (Do you think that primates weigh economical benefits of having children before they decide to mate?) If the male is not attracted by females, he will be at a disadvantage.

      A better explanation would be that, as JS says, there’s a biological process that’s supposed to lock the person into heterosexuality, and it occasionally malfunctions, which happens much more often in the modern society than among hunter-gatherers. Sexual identity develops between the ages of 8 and 16. For all its advances in “sexual freedom”, our modern society is extremely prudish whenever questions of sexuality and children are involved. Like you said, many foragers have no concept of homosexuality, but the same foragers have very different concepts of acceptable sexual behaviors and, more generally, acceptable exposure to sex among adolescents. There are no adult homosexuals among Hadza foragers, even though they don’t have any social taboos against that. But it is considered normal among them for 8-year-old kids to engage in sex play (either heterosexual or homosexual, both ways do occur). And the kids come out of that firmly locked into heterosexuality.

      On the other hand, a Western 8-year-old kid might still believe that “children are bought in a store” and the society will go to extremes to protect him from any exposure to sexual concepts, sometimes to the extent of confining him or her to a single-sex boarding school. The end result is a rich variety of sexual deviations, from homosexuality to pedophilia to furry fandom.

      • misdreavus says:

        So apparently a biological drive which is *fundamentally essential* for the propagation of the species, and thus ought to be resistant to subversion toward non-productive means by facile environmental stimuli, happens to be so malleable that a minor cultural change is sufficient to trigger male homosexuality in _three_ percent of the adult male population. Why, it’s not like evolution has optimized the mammalian sex instinct over tens of millions of years, or anything. Clown.

        You know, this reminds me of when the feminist scholar Naomi Wolf claimed that hundreds of thousands of American women were starving to death each year due to eating disorders. Purportedly because the media and culture brainwashes them to conform to unrealistic standards of thinness, or something.

        As it turns out, the actual figure is in the low hundreds. For some gosh darned strange reason, it is extremely difficult to convince people to voluntarily starve themselves to death. I wonder why this is?

      • nameless37 says:

        Why do you think that it’s a “minor cultural change”? It’s drastic and unprecedented. We’re talking about a total ban on sexual experimentation, physical contact and even less-than-fully-clothed exposure between adolescents of opposite sexes. I can’t imagine this being the situation in any prehistoric humans.

        BTW, mammalian sex instinct is much more variable than you think. Chimpanzees are the closest species to humans, and yet their sex instincts function very differently from ours. For starters, humans are about the only mammalian species where females don’t exhibit any overt signs during periods of sexual receptivity. When a chimpanzee female ovulates, every male in the neighborhood knows about it. When a human female ovulates, chances are, she does not even know about it herself.

    • teageegeepea says:

      If homosexuality did not reduce fitness in the past, why did heterosexuality evolve in the first place?

  13. Dystopia Max says:

    While you’re counting corpses and babies, did you ever consider responding at length to the hypothesis of homosexuality as a likely risk/outcome of a man absorbing his female twin in utero? I know he’s an intel analyst and not a scientist, but I remain quite impressed with Welmer’s outline of the chimera hypothesis. And he name-checks you in the first paragraph:)

  14. erica says:

    “In the past, homosexual orientation was not fitness reducing in most human population groups, because the homosexual identity had not yet been invented.”

    So, you’re of a mind that there aren’t homosexuals who can’t get it up for/with women? Have tried, failed, and so give up, or are so disgusted by the thought initially that they don’t try at all?

    You’re arguing that all or most gay men in the past could perform with women, and further that they not only could but that they did so to the degree that their genes were not out-competed by those of straight men?

    It’s impossible for me to believe that in the past gay men who could perform with women and have a few kids had as many kids as the straight man. Some of those times he rolled over and looked at the woman in his bed, he must have chosen instead to throw on his clothes and hightail it out to the alley where he got what he really wanted, or settled for sleep, or maybe self-gratification. Result: over the long haul, fewer kids from them than from the straight guys, fewer genes left in the competitive stew. And this is only considering those who could perform.

    • Juan Valdez says:

      “So, you’re of a mind that there aren’t homosexuals who can’t get it up for/with women? Have tried, failed, and so give up, or are so disgusted by the thought initially that they don’t try at all?”

      There are probably a lot of male homosexuals in modern Western societies who can’t get it up for women. But the question is, would they have been able to get it up for women if they had been raised in a society with different attitudes towards homosexuality? Would they have been able to get it up for women if they had been raised in a society like the Aka where nobody has even heard of homosexuality, but heterosexual sex is constantly on display multiple times per night?

      It is suspected that conditioning (learning) plays a role in the development of partner preference, along with genetic and hormonal factors. Coria-Avila (first paper below) suggests that partner preference in adult animals was not merely the result of genetics and hormones, but that it had been “narrowed down” through learning. Scientists were able to use classical conditioning to cause sexually naive rats to develop a learned homosexual partner preference. They were able to do the same thing with quail.

      I’d suggest that many of today’s homosexuals have narrowed down their partner preference to the point that they can no longer become aroused by the opposite sex. I’m not sure that this would have happened if they’d have been born as Aka pygmies.

      Meanwhile, we’re pretty sure that many of today’s young, biologically healthy heterosexual Western males have narrowed down their partner preference to the point that they have erectile dysfunction with real women and can only become aroused with pornography. Same mechanism at work, I think.

      • nameless37 says:

        This view can actually be harmonized with my theory above.

        Most gay males develop a sense of “sexual difference” from the others by the age of 17. I just found an article with surveys of such males about their feelings and experiences in ages 13..17. Asked whether they agreed with statements that “opposite-sex sexual relations were somewhat unsatisfying” and “homosexual activity was more satisfying than heterosexual activity”, respectively 9% and 2% answered “yes”. (a bit old, but surely still accurate.)

        I interpret this as a sign that, by the age of 17, the overwhelming majority of gay males have no experience of heterosexual activity.

        It’s much easier to for the “wrong” partner preference to imprint if you’re prevented by the society from trying the “right” partner preference until you’re too old to correct.

      • nameless37 says:

        Also, someone should do a similar poll among furries. I’d bet the farm (ok, not the farm, I don’t have a farm, but I’d bet $20) that the percentage of furries reporting no prior heterosexual experience by the time they self-identified as such would approach 100%.

  15. observer says:

    What are your thoughts about the argument that homosexuality is the result of sexually antagonistic selection, put forth by Camperio Ciani?

    “We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait.”

    I think there is a more recent article along those lines as well but I can’t seem to find it at the moment.

    • gcochran9 says:

      Since no one can find such a gene in a GWAS survey, he’s wrong. He was likely to be wrong anyhow. First, men who know this literature better than I don’t believe his data – don’t believe in higher fitness in the female relatives. Second, and I’m sure about this – greater fertility in female relatives would not give much of a boost in fitness, because resources have been more of a limit on fitness than fertility – certainly over the past few thousand years. Greater fertility does not produce bread.

      Third, if an allele had negative effects in males, you’d expect to see modifier genes evolve that simply shut it off in males. The more deleterious the effect, the more rapidly this would occur.

      • Lemniscate says:

        I would also expect exclusive female homosexuality to be much more common than exclusive male homosexuality, as the fitness of hyper-fertile men (possibly leading to homosexual daughters) is far greater than the fitness of hyper-fertile females (possibly leading to homosexual sons). As far as I’m aware, exclusive female homosexuality is rarer than exclusive male homosexuality.

    • erica says:

      I think this is probably the more recent one to which you refer:

      They admit to small sample size.

  16. Holm says:

    A couple of old dads with gay/transgender sons…
    Warren Beatty’s Transgender Son

    Woody Allen’s gay son Satchel…

    • erica says:

      Hmm. Looks nothing like Woody, a lot like Mia. Also looks as if he’s had recent Botox injections in those lips.

  17. misdreavus says:

    Speaking as a gay male, the germ theory of homosexuality makes more sense to me than any of the others I have encountered in my lifetime. Too bad it’s not very politically correct — otherwise we might identified the offending pathogen long ago. Then again, microbiology itself isn’t as robust of a discipline as we would like to think — something like only a fraction of a percent of all bacterial species that exist have been characterized, and viruses are even more elusive.

    Homosexuality indeed has a very low concordance among identical twins — according to the most robust twin studies we have available, the heritability of male sexual orientation is less than 0.3 — not the fifty-fifty cited in most psychology textbooks. A quick survey of the anthropological literature indicates that it is not ubiquitous across human cultures. Nor does it result in higher fertility among female siblings — if this were the case, you wouldn’t even need to quantify the selectionary benefit, you could see it with your very eyes. To the best of my knowledge, not a single culture on Earth has developed a mythology where gay sons are considered a omen of fertility because of the benefit they confer on their sisters. Scientists who push the gay uncle hypothesis apparently failed middle school algebra.

    Whatever is responsible for male homosexuality, it has to be something be so powerful that it confounds the power of human evolution, particularly for adaptive traits that have been optimized over tens of millions of years (at the least). Cultural change won’t do it. Homosexuality is maladaptive in all social situations, not just a few. Genetics doesn’t explain it at all — at the very best, it serves as a distal cause or risk factor, not a primary one. Differences in parenting indeed have nothing to do with homosexuality, but they have nothing to do with *everything* from IQ to personality, not just sexual orientation. As for the chimaera hypothesis, differential exposure to androgens in utero, or “epigenetics”, horse crap. Fraternal twins are no more likely to be concordant in sexual orientation than ordinary siblings. You would think educated people, particularly scientists in the field, would learn to browse through the relevant literature before postulating wildly and making fools of themselves.

    As it turns out, there are critters in nature that evolve very quickly, on the scale of *hours*, not just years or centuries, and are thus capable of overpowering even the sturdiest of human biological impulses. Some of them have been proven to alter cognition and thinking. Uh-oh.

    • gcochran9 says:

      Surely you’re speaking as someone who can count, which is apparently a lot rarer than homosexuality.

      • misdreavus says:

        But that is hereditary, to a large degree, and homosexuality isn’t. If only!

        • gcochran9 says:

          I think that a pathogen is the most likely explanation proposed thus far – although I would think that, wouldn’t I? Others, Bill Hamilton for example, thought it made sense, which is not the same as saying they thought it was proven. Maybe there’s some correct explanation that nobody has imagined. Haldane suspected that the Universe is not just queerer than we suppose, but queerer than we can suppose.

      • nameless37 says:

        The problem with pathogen theory is that, I think, it affords an unjust and unusual preference to one specific sexual deviation: homosexuality. We know about a wide variety of deviations. At one extreme, there are deviations which are demonstrably caused in a large fraction of cases by extrinsic disruptions of normal sexual identity development, and considered “mental diseases” because they are harmful for the society (pedophilia). At the other, there are deviations which are, again, obviously caused by the failure of normal sexual identity development to take its course, but considered to be “quirks” or “within normal range of human sexuality” because they are totally harmless (furries or porn addicts). At the edge between “normal” and “harmful” there is homosexuality, which only accounts for a few % of the population, has a vocal activist community, represents a very unusual lifestyle, and stirs a lot of debate because of its borderline status.

        Objectively, one should ignore the activists from both sides and try to view the problem in its wider scope, as one of the many ways humans end up with attachments to “wrong” sexual objects. Pathogens might sound logical if we look at homosexuality as a unique disorder and we don’t know about any others (or consider others to be unrelated), but not if we look at it as one of the family of disorders where some other disorders are easily explainable without any pathogens or infections.

    • erica says:

      “Nor does it result in higher fertility among female siblings — if this were the case, you wouldn’t even need to quantify the selectionary benefit, you could see it with your very eyes. To the best of my knowledge, not a single culture on Earth has developed a mythology where gay sons are considered a omen of fertility because of the benefit they confer on their sisters.”

      Yes, something like that would be an “everybody knows” kind of thing: “You know, your Aunt Mary and my Aunt Sally both have homosexual sons and as a result have no grandkids from them, but they sure do have a lot of other grandkids from their other kids.”

  18. misdreavus says:

    nameless37, to what extent do any of these paraphilias result in a loss of evolutionary fitness? Judging from what we know about pedophilia, which is almost exclusively a male disorder, only a tiny minority of pedophiles are of the exclusive variety (e.g. only attracted to pre-pubescent children). Sexual orientation in adult males, on the other hand, tends to follow a hook-shaped distribution. The vast majority of men everywhere score either one or six on the Kinsey scale.

    Your hypothesis explains absolutely nothing, and moreover, it flies in the face of the anthropological literature. Homosexuality is very rare among certain Bedouin Arabs (in particular the Rwala tribe of northern Saudi Arabia), some of whom practice regimes of sexual apartheid that would make Mullah Omar blanch. You can’t get any more socially conservative than that. Why the hell does modern society cause _certain_ people to go awry in the development of their sex drive and not others? You might as well claim that a magical fairy causes 3% of the population to turn gay at random.

    Then again, perhaps a dominant, overbearing mother and a weak, submissive father might also play a significant role in the etiology of homosexuality. Maybe homosexuality is a misfiring of the Oedipal complex during the anal stage of childhood. Maybe, as Margaret Mead opined, we are all born bisexual, and it is society that forces us into binaries of sexual orientation. Maybe it’s demonic possession. Or maybe it’s waves of harmful radiation coming from cell phones. Or maybe, as Foucault wrote, homosexuality is a cultural artifact, and was socially constructed in recent historical times. Who knows, maaaann.

    • nameless37 says:

      I’m not sure why you’re asking about evolutionary fitness. Since my point is that homosexuality is an acquired trait that has to do with exposure to the opposite sex between the ages of 8 to 16, evolution is entirely irrelevant here.

      I haven’t looked at this for a while, but I believe that you’re incorrect that exclusive pedophiles are a tiny minority. It may be a minority but it’s a substantial one. And exclusive pedophiles are formed in many cases through sexual abuse in childhood. So that’s one excellent example that shows that messing with one’s pre-pubescent sexual experience has a good chance of leaving the individual with warped sexual identity.

      It’s strange that you’d bring up Saudi Arabia Bedouins as a counterexample. Saudi Arabia is one of the hot spots of child slavery in the world, and Arabs in general present some of the most extreme cases of warped sexual attitudes that even most Western homosexuals would probably find appalling (I recall reading that boy sex slaves were consistently valued higher than girl sex slaves there). It’s the case of a clash between pro-deviance sexual patterns and conservative Islamic governments that consider all deviant sex a crime punishable by death.

      To quote The Time (1966):

      “Homosexuality is something of a tradition in backward Yemen, where Bedouin herdsmen roam the rocky hills for months on end with only each other and their animals for company. Male brothels flourish in San’a, the capital, and the late Imam Ahmad, who ruled the country for 14 years before his death in 1962, established an international reputation for overzealous camaraderie.”

      • misdreavus says:

        “but I believe that you’re incorrect that exclusive pedophiles are a tiny minority.”

        Well you could believe whatever the hell you like, and make shit up as you go along. Or, alternatively, you could look at the actual literature. It’s entirely up to you.

        “Male brothels flourish in San’a, the capital”

        Just stop. Please. Have you even paid any attention to anything I’ve written thus far?

      • misdreavus says:

        Google is your best friend. Here you go:

        “Pedophiles are subdivided into several classifications. One of the first distinctions made when classifying pedophiles is to determine whether they are “exclusively” attracted to children (exclusive pedophile) or attracted to adults as well as children (nonexclusive pedophile). In a study by Abel and Harlow15 of 2429 adult male pedophiles, only 7% identified themselves as exclusively sexually attracted to children, which confirms the general view that most pedophiles are part of the nonexclusive group.”

        Mayo Clinic Proceedings – April 2007 (Vol. 82, Issue 4, Pages 457-471, DOI: 10.4065/82.4.457)

      • nameless37 says:

        I may have been wrong in this aspect. In any event, this is a totally orthogonal issue to the subject at hand.

        Since you say that you are a gay male, there’s a much better way that you can prove me wrong. Would you care to share the age when you had your first experience of a fully naked female?

    • nameless37 says:

      ” Why the hell does modern society cause _certain_ people to go awry in the development of their sex drive and not others?”

      Humans are predisposed towards heterosexuality. However, actually realizing that predisposition requires adequate exposure to the opposite sex. When the society prevents that from happening, the individual gets locked onto whatever alternative source of sexual arousal that remains still available. Sometimes the predisposition gets overwhelmed by a combination of factors, including failure to get some sexual experience with a live human girlfriend before the age of 16 (particularly one that you can experience when she’s not fully clothed) and an exposure to a sexually attractive male role model.

      • greg kai says:

        This is not really in line with homozygote twins having different sexual orientation, almost with the same probability as general population, when they had the most similar childhood experience and parenting one can imagine. Or do u think it is linked to one twin having the chance to hit a gf, while the other did not? I can not believe this…
        It may be that sexual preference is triggered by some events (although it would have to be well before 16, well before 12 I think….cause child behavior is already often markedly different for mal homosexual before that) and so quite fragile in fact….but the factors you mention do not look likely to me….

      • nameless37 says:

        “Or do u think it is linked to one twin having the chance to hit a gf, while the other did not? I can not believe this…”

        Interesting point. That would be my contention, yes.

        “.cause child behavior is already often markedly different for mal homosexual before that”

        Is it? From what I read, there’s talk of male homosexuals “feeling like they don’t belong” prior to the age of 16, compared to male straights … big whoop … If I had $1 for every straight child that felt like he didn’t belong to his peer group, I’d be a multimillionaire. Also, can you distinguish between behavior that occurs because one’s a homosexual, and behavior that occurs because one belongs to a social group that’s statistically unlikely to get girlfriends?

      • greg kai says:

        It’s not “feeling like they don’t belong”, typical of late childhood, that I had in mind….more the “Childhood gender nonconformity”….Like boys playing with dolls and trying makeups, all of this well before 10. It is reported as quite strongly correlated with homosexuality when adult….BTW, this noncomformity also means the child have playmates mostly of the opposite sex, while typical behavior at this age is same sex playmates. Again, this is quite opposite to your theory imho…
        Reagrding groups which tends to have gf later than average, I guess nerds fit right in. They are not gender non-conformal though…maybe less sports, but a lot of hard sciencie and tech interest which is hypermasculine. And, afaik, they do not exhibit higher homosexuality when adult. If anything, they have less…

  19. misdreavus says:

    There are certain morons who still espouse the notion that “society” is a metaphysical construct that is wholly independent of the confines of biology and neuroscience. (That would be just about all important researchers in the social sciences.) Hell, as Aristotle once observed, maybe the brain really does exist merely to cool the heart.

    Calling homosexuality a product of society explains absolutely zero. Calling it a product of social conditioning explains absolutely zero.

    Correctly observing that it exists in certain cultures, and not in others, explains absolutely zero. Claiming that it is a social construct explains absolutely zero.

    Gee, why the hell do I even bother.

  20. misdreavus says:

    “In any event, this is a totally orthogonal issue to the subject at hand.”

    Nope. In fact it is THE defining issue at hand. Homosexuality wouldn’t need any explanation if it didn’t slash your reproductive fitness, while simultaneously affecting 3-5% of the population. It’s about as mysterious as three percent of bears hibernating in the summer, rather than the winter. Or three percent of cats preferring kohlrabi to pigeon entrails. Selection does a very efficient job eliminating alleles that contribute to such aberrant behaviors. If you don’t believe it does, you are a creationist.

    We know that individuals who are exclusively attracted to pre-pubescent children are extremely rare — the criminological evidence speaks for itself. None of the paraphilias you mentioned diminish reproductive fitness to the same extent as homosexuality.

    And if you believe otherwise, let’s take a good look at the internet search histories of all those furries and assorted freaks on 4chan. If they’re as common as you think they are, they probably enjoy a healthy range of sexual appetites.

    • nameless37 says:

      But I fully believe that homosexuality is not genetic! Did I give you any reason to think otherwise in any of my posts? Homosexuality is entirely situational.

      Maybe it might make you feel less confrontational if I admit that I am, in fact, a furry. (Or, at least, I was 5-ish years ago, Currently I’m a father of 3. That did not really change my sexual attitudes. After all, my first true sexual experience occurred when I was 23.)

      • misdreavus says:

        “Maybe it might make you feel less confrontational if I admit that I am, in fact, a furry.”

        Oh sweet Jesus! I can’t stop laughing.

        Speaking as one mentally ill male to another, I’m afraid that’s probably the least of your cognitive problems, dear.

      • nameless37 says:

        It’s good that I made you entertained, that’s about the extent of my intended objective here.

    • erica says:

      My gawd, I had to look up “furries.” It didn’t sound too good, and by gawd, it isn’t. And I thought Trekkies were whack-o.

  21. Juan Valdez says:

    Well, nameless37 raises a good point. Arabia, Afghanistan and the United States have a couple of things in common. Puritanism, homosociality (non sexual relations are primarily with the opposite sex) and rampant homosexuality. Coincidence, maybe maybe not.

    Compare to these societies to the Aka pygmies, where masturbation and homosexuality don’t exist.

    We’re told that the Aka married couples have sex three to four times per night, each night, even during pregnancy (!). The article doesn’t go into their child raising practices too much, but it does mention a group of children stealthily watching couples having sex and then making up a song about it. We can probably infer that children have a fair amount of opportunity to learn about heterosexual sex, at least through observation.

    The ancestral environment in which humans evolved also provided a fair amount of opportunity for early learning regarding heterosexual sex. If you doubt the importance of conditioning on partner preference, see the two papers I linked above.

  22. erica says:

    “Well, nameless37 raises a good point. Arabia, Afghanistan and the United States have a couple of things in common. Puritanism, homosociality (non sexual relations are primarily with the opposite sex) and rampant homosexuality. Coincidence, maybe maybe not.’

    Come off it. The Scandinavian countries can hardly be accused of being sexually Puritanistic, yet their numbers approximate those of “Puritanical” America.

    You are ignoring what poster greg kai said.

  23. Anon says:

    I thought homosexuality had something to do with improper amounts of testosterone being applied to a developing brain en utero. For men, not enough, for woman, too much.

  24. misdreavus says:

    This thread is proof that the internet allows crazy people (who would otherwise never know of each other’s existence) to congregate in large numbers.

    Well, maybe I’ve contributed plenty of craziness of my own. But hey, at least I don’t masturbate to the Island of Dr. Moreau.

  25. Greying Wanderer says:

    Apologies for being completely off-topic but i was struck by a random thought vis a vis the decline of violence. What if we’re looking at it the wrong way round?

    What if men with either a high propensity or high capacity for violence *always* have a disproportionately high death rate in all environments e.g.

    1) In a tribal raider culture
    – killing each other.
    2) Under civilization
    – getting executed in peacetime.
    – getting killed disproportionately in wartime
    – killing themselves doing dangerous stuff for fun when they’re bored
    – getting self-destructive when there’s nothing to fight

    so there’s a permanent tendency for pacification to occur over time and it’s *only* in a tribal raider (or gangsta underclass) environment that their reproductive success outweighs this higher death rate.

    • Probably you are right but you are assuming that the right “baseline” is decent peaceful societies. We could look at it the other way and take our baseline as warrior cultures. This goes to the argument in anthropology about the “EEA” and what it was. The convention of the last ten years or so has been that the EEA was !Kung Bushmen but there is no support for such a picture.

      • Greying Wanderer says:

        “Probably you are right but you are assuming that the right “baseline” is decent peaceful societies.”

        No, not at all. I’m assuming the norm is an extremely violent warrior culture but that the mechanism that maintains it is the other way round. Instead of the violent traits reproducing themselves by default unless some pacification process is applied to them what if violent traits have a built-in tendency to diminish through their very nature – higher death rate – and are *only* replenished enough in warrior cultures where being the fiercest means more offspring?

        In that case there’d be a natural decay rate – say 1% for the sake of argument – needing the lawmen to find the last 0.5% to get to the 1.5% you mentioned in your post?

  26. Greying Wanderer says:

    “For starters, humans are about the only mammalian species where females don’t exhibit any overt signs during periods of sexual receptivity. When a chimpanzee female ovulates, every male in the neighborhood knows about it. When a human female ovulates, chances are, she does not even know about it herself.”

    women turn into werewolves when they’re ovulating. you may need to be (or have been) cute to know this.

  27. Greying Wanderer says:

    If the gay bug idea is correct wouldn’t it make sense for it to have developed initially as a promiscuity bug then maybe evolved to promote or reduce resistance to bisexuality?

    Going to far and causing exclusive homosexuality may have been a mistake (or a recurring mistake).

    • gcochran9 says:

      Only if its effects are a direct strategy – doesn’t look as if they are. But something like what you’ve suggested does exist, in cicadas. There’s a fungus that infects and destroys the abdomen, rendering the cicada unable to mate. But they survive, at least for a while, and exhibit courtship signaling – but to cicadas of both sexes. They constantly signal, and constantly approach other signaling cicadas. They try to hard to make physical contact. It’s probably host manipulation. Put this on the list of interesting bits of biology that we can be thankful don’t happen in humans.

      • anneallen3 says:

        so what is the strategy of the gay bug which indirectly causes human male homosexuality?

      • Greying Wanderer says:

        “Only if its effects are a direct strategy – doesn’t look as if they are”

        Just realised the promiscuity idea doesn’t make sense with gay toddlers (assuming that’s true) unless it was a weird side-effect.

    • Richard Sharpe says:

      Is it possible that this ‘bug’ is something that most people are immune to during the critical development phase where it kicks in?

      • anneallen3 says:

        MZ twin discordance at 80% seems to indicate that “proposed” critical period would be post natal but (from reports that gay males are gender dysphoric as toddlers) must be early post natal. Molecular mimicry is responsible for a host of autoimmune diseases, for example: psoriasis is associated with streptococcal infection. Rheumatoid arthritis, type 1 diabetes, MS…all are examples of diseases probably caused by MM…

  28. JayMan says:

    Dr. Cochran, what do you think of the study by Zietsch et al, that the same-sex heterosexual twin of gay men have greater number of sex partners than the heterosexual average?

    Upon taking a closer look at it, while it relied on a large twin sample, the total number of homosexuals is small, so any conclusion they try to make has relatively low statistical power. This is along with other problems like the reliability of self-report number of sex partners, etc, it seems.

  29. The fourth doorman of the apocalypse says:

    If there was a member of the genus Ovis where a significant number of males were only oriented towards other males, what would this say about possible mechanisms? Would it have any relevance to the case of same-sex sexual orientation among males of Homo sapiens.

  30. I apologise for not noticing this post until the thread was too long to attract the clicks of most readers. I’m an hbd-believer, psychiatry-as-science encourager, and psychiatric social worker (that’s an extremely rare triad) who has a fair bit of data, and experience in these discussions. Also, my opinions are right, though that is a separate matter.

    I’ll try and be more alert.

  31. Pingback: A Gay Germ? Is Homophobia a Clue? « JayMan's Blog

  32. rob says:

    Besides that, we (I have a tapeworm)…

    hahaha. In Soviet Russia, tapeworm has you!

  33. Shooter says:

    Erica is wrong. “There has never been a successful attempt at changing someone’s sexual orientation” – that is refuted by 100 years of evidence. The claim that homosexuality is irreversible suggests that it is innate, which it is not.

    More homo-logic. Beautiful.

  34. philosophe22 says:

    Curious what any of you think about this research: “Enhaced D2-type receptor activity facilitates the development of conditioned same-sex partner preference in male rats.” Seems to show that sexual preference can be conditioned in virgins. Here’s a slideshow that tries to tie this research with overconsumption of Internet porn to sexual conditioning:

  35. Pingback: Greg Cochran’s “Gay Germ” Hypothesis – An Exercise in the Power of Germs | JayMan's Blog

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