Why is something that obviously should well be evolutionarily wiped out (if it is indeed due to genes/people can't help it) not, by now?
(Corollary question if you say "there is no evolution, it's intelligent design" - ok then what the heck purpose would homosexuality serve in this design? Honest question, I'm not being a smartass.)
Edit - PS you know you're over some kind of target if an OP gets downpoots.
Its a perversion of nature....according to ancient metaphysics when conception occurs the male or female sex dna code arises together with the consciousness of the being. Extreme rare cases of karmic error may give rise to double or corrupted ( imperfect) sex code, as results due to influences of karma, consciousness, weather, nutriment.... as now in age of mass perversion, delusion, corrupted code occurs frequently... many cases of gayness are due to social persuasion combined with habit of craving desires or conversly due to induction or abuse..these are more mental ( social)/causal factors, nurtiment could possibly create abnormality, though less likely, as would weather.