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.
Homosexuality in nature almost exclusively occurs because of one of two reasons:
The animal is so horny during its respective mating season that literally anything they can shove their dick into will suffice just so they can turn their horny brains off.
As a sign of domination of lesser peers, most notably within pack-animal hierarchies.
Homosexuality is never a result of the animal actively dismissing its role in procreation in order to pursue the same sex and appease fetishistic sexual desires. Animals have no capacity to think "I must only have sex with my own gender because I am gay."
Animals think "food, comfort/shelter, make babies, avoid scary things." They simply can't think of much else without humans coming along to actively screw with their behavioral psychology.