As Sabretooth said, evolution and genetics would have WIPED out any "Gay Gene," long ago.
Sex for anything other then reproduction is the result of personal experience IMHO. Not to get to weird but I find the following example to be useful when trying to describe genetics...
Lets say Aliens visited the Earth(I know, I KNOW!), if they were attractive human looking folk then I will bet several groups of humanity would LOVE to have sex with them. That would definately happen if the circumstances were right. Also, some would be wary of the aliens and others would have sex with them. Is THAT genetic? How can it be? There have never BEEN any thing other then humans on the planet. How about bestiality, is THAT genetic? Why? It makes no scientific sense.
Some people like blondes, some dont. IS THAT genetic? IN maximum security prisons for hard timers, homoism exists among virtually entire prison populations. Is THAT genetic?
It seems to me that the Homosexual Lobby feels so guilty unconsciously that they want to MAKE the world approve. Even more ironic is the fact that they are so insecure as to forego personal responsibilty for thier homosexuality. If I were a fag, I would not shrink under the label "Nature made me do it!" The Homosexual movement itself has factions which question the value of calling it genetic.
I think Liberal Straight folks have done more to advance the FORCED acceptance of Homosexuality then the Homosexuals themselves.
PHEW!
That seems to be a sensible explanation.