Simon, I think the emphasis on genes goes back a while when being gay wasn't so excepted and there was a number of genetic studies sponsored by the gay community to find the gay gene. Its been discredited now as far as I am aware. The matter of genes is complex but whatever your genes and disposition......much more influential is your life/upbringing. That has a massive effect on how you develop, so much so any genetic predispositions are largely irrelevant.
ISP