Work with me:
1. Cultures and societies that persecute homosexuality exert pressure on homosexuals to remain closeted and lead normal lives.
2. Their efforts to appear normal include getting married and having children.
3. Genes/dispositions/influences for homosexuality spread further down the family tree.
Summarized from this comment:
It seems to me that cultures which mandate reproduction and persecute homosexuality will have higher numbers of homosexuals if it is genuinely genetic, because in those societies homosexuals will be more likely to marry the opposite sex and reproduce, in order to avoid identification and persecution.
The researchers discovered that women tend to have more children when they inherit the same – as yet unidentified – genetic factors linked to homosexuality in men. This fertility boost more than compensates for the lack of offspring fathered by gay men, and keeps the “gay” genetic factors in circulation.
I always felt that it made sense for social mammals to have homosexuality because it would take one or more males out of the always fierce competition for stud rights and pack dominance and the “gay uncle” phenomenon (seriously) within packs would mean more males spending their time protecting young and working to find water and food.
This seems like the most sensible explanation for male homosexuality in the social mammals. The fewer men spending time breeding/competing, the more men there are to protect, care, forage and hunt.
Not sure how this applies to female homosexuality – though sex between two women seems like it would be good for tribe cohesion just like it is for sex between two men.
At the same time, to frame these issues in gay/straight dichotomy instead of a broad continuum of sexual preference, attraction, activity and the simple fact that humans will mash their genitals together whenever, whatever in any permutation you can imagine – there’s a reason we have endorphins.
So once homosexual men and women are completely accepted as total and equal members of societies, there won’t be any more passing along of those genes and genes/dispositions will be bred out of the gene pool – until then gay couples can help take care of surplus offspring and advance society while all the breeders are weighed down with propagating the species.