In every population, some people have serious problems with alcohol, but this happens more in some populations than others. In particular, populations with low or nonexistent historical exposure to alcohol have higher rates of alcoholism. Hunter-gatherers all seem to have serious problems with alcohol. The Hadza, Bushmen, Pygmies, Australian Aboriginals, Andaman islanders, and Eskimos all have a high percentage of lushes.
Now this all makes sense: alcoholic beverages are mostly made from domesticated plants, and hunter-gatherers didn’t have much exposure to them. Alcoholism has high heritability, and it’s bad for you: you’d expect it to decline over time, be less common in populations that have been drinking for a long time, all else equal. In East Asia, many people have a bunged-up version of acetaldehyde dehydrogenase, the enzyme that converts acetaldehyde into acetate (after alcohol has been converted into acetaldehyde). This makes drinking so uncomfortable that carriers are highly resistant to alcoholism. They don’t need to buy Antabuse – the effect is built-in.
Distribution of the ALDH2*504Lys allele
This Chinese mutation was definitely selected, maybe for protection against alcoholism, but possibly for some other reason.
So in China a lot of the story is in one gene, but in other populations, resistance to alcoholism is polygenic.
All this is fairly obvious, but my impression is that cultural anthropologists, and for that matter right-thinking people generally, don’t think that genetics has anything to do with different rates of alcoholism in different populations. Probably libertarians don’t think it does either, although they undoubtedly have different wrong ideas about this.