I don't think there is any "gay gene." But even if there were, your observation here seems both obvious and irrelevant. Obvious, because if you could hypothetically removed societal influence, people who weren't particularly attracted to procreative sex wouldn't do it, and they would die out in a generation.
But irrelevant, because there have never been human beings who lived in what is foolishly called a "state of nature", outside of a social context with all its cultural, economic, and psychological influences. Such influences have always operated to encourage man-woman bonding and family formation, because that is the foundation of human flourishing across the generations in every culture.
I know that you don’t believe there is a gay gene. I sure hope I didn’t imply otherwise. If so, please forgive that as poor communication on my part.
My point may be obvious but I don’t think it’s irrelevant. Those who push the mythical gay gene claim that homosexuality is genetic, is not a choice, and is not influenced by societal factors. Without societal influence, the mythical gay gene would cease to exist. They can’t logically claim that homosexuality is purely genetic because “pure genetics” wouldn’t allow it.