India today is made up of innumerable jatis, most of which have been endogamous for thousands of years. Most do not seem to have experienced consistent directional selection for interesting traits ( No Kwisatz Haderachs or Guild Navigators), so they have the costs of long term endogamy ( inbreeding depression) without any obvious benefits.
But this genetic situation, unlike most, has a simple solution: marry outside the jati. Although that’s not so simple – if it were, jatis would not have stayed endogamous for so very long..
The way forward is the revival of an ancient custom, one common back in the poorly documented days when India had airplanes and spaceships: ‘jati marriage’, the complex ritual in which two jatis form a bond that allows their members to intermarry. It is little known today, because of India’s weak tradition of historiography, and because I just made it up. It has very real benefits: the children of such unions would be smarter, healthier, & taller. Note: reviving an ancient custom is the exact opposite of being a soulless innovator with no cultural roots, even if it means doing exactly the same thing.
Traditionally, the two jatis (which are generally spatially adjacent and of similar social rank) go through a long period of testing and negotiation, exchanging gifts, comparing bank balances, and deciding who will be on top. The deal is finally sealed with a musical extravaganza, with hundreds – no, thousands ! – of people showing Bollywood how it’s _really_ done.