It is not too uncommon to see stories of closeted gays marrying and having children. It is safe to presume, then, that this practice was even more common in the past when homosexuality was much less accepted.
Also, even if you rule out a genetic origin, it could still very well be biological. Prenatal hormones and the structure of the brain seem like more logical origins.
I agree completely that it could still have a biological cause. However, let's assume that there is a gay gene, it would have to be recessive or else there would be far more homosexuals. Therefore you would need two identical
alleles, which would have a VERY low possibility, because you would have to have a gay man have a child with a lesbian.
I don't think you have a complete grasp on the basic model of genetics and the recessive trait
I actually do, but when I was writing this post I failed to take into account 2 heterosexual parents carrying the recessive homosexual gene. Even still, I find it rather unlikely that sexuality would be genetic, considering there are so many "variants" of sexual preference (completely homosexual, bisexual, asexual, pansexual, heterosexual, transexual).
It's not that simple. First of all, if there does happen to be a "gay gene" or a gene that inclines people to be attracted to the same sex, it could have been passed on because it is not impossible for homosexual men to marry women and have children with them which was very common in the past when homosexuality was less accepted. Second of all, a lot of evolutionary studies have shown that homosexuality can have an indirect benefit on a species.