I think I remember this from biology. It has something to do with the mother’s body rejecting the boy because of the difference between the fetus’ XY chromosomes and the mother’s XX. As the mother has more boys, her body becomes more adept at attempts to ‘feminize’ the boys, ultimately increasingly the likelihood of a gay son. There’s more to it, but that’s the basic gist of it. It was interesting, if nothing else.
Joke aside I really hate that theory, because it basically falls into the “gay=feminine” ideology which is not only incorrect but very harmful considering “feminine” is the reason that many gay and straight men (including children) are assaulted and murdered.
The theory itself revolves around the uterus rejecting amounts of testosterone and replacing it with estrogen. I can say from the sheer amount of body hair I have that I am not lacking in testosterone. I can also say that the internalized homophobia against “fems” vs “mascs” comes from the same homophobic shit as “feminized” babies. Masculinity has nothing to do with having a penis. Sexuality isn’t something that happens due to a generation gap. If this were the case, hormone therapy would “cure” my homosexuality. Not a fan.