If being homosexual was hereditary, it would have been bred out of the species millions of years ago. Even the trait of being “susceptible” to being gay would have been bred out. As far as I’m concerned Cain is 100% on this....it’s “nurture” not “nature”.
There are any number of genetic diseases that kill their victims at a very young age. By your logic those should have disappeared as well. As should conditions like autism, since very few people who suffer from that produce offspring.