I love that most of this thread follows the straw-man argument of genetics. Consider, if you will, the possibility that homosexuality is neither a matter of genetics nor a matter of choice. Imagine for a moment that there exists a gray area between these possibilities, wherein lies the deeply wired psychological clockwork formed by the experiences of a human brain in the early stages of its development. Those same early stages wherein men form Oedipal complexes and breast obsession. You religious types are correct in one respect: you choose who you marry, who you have sex with. What you forget is that you don't choose who you -want- to marry or who you -want- to have sex with. If those kinds of preferences were a matter of choice there would never be a difficult breakup or an unhappy relationship. When you figured out that you and your partner were incompatible, you would simply choose to prefer someone else and the two of you could go about your lives without a hard word exchanged. Even preferences in areas as innocuous as food and movie genres are too deeply programmed into your psyche to just "choose" your way in and out of them. If you hook up with a girl that's really into Sundance type arthouse flicks, and your favorite movie was Transformers Dark of the Moon, you can't just "choose" to like artsy independent movies better than big budget action flicks so that you and your new friend can relate better. You can choose to watch them with her, but you can't decide for yourself whether or not they're gonna match up with your sensibilities. If you fall on hard times, you can grind up some rat meat and pretend it's a cheeseburger, but you can't "choose" to actually prefer rat meat to beef if you don't already. It simply doesn't work that way.
That said, it's just as ignorant to claim that "everyone knows you're born gay or straight". Actually, nobody knows. The combined genetic knowledge of our entire species isn't yet sophisticated enough to confirm or deny the existence of a homosexual gene or a specific genetic mutation that leads to homosexuality. To my thinking, it's not likely that it's a genetic trait, any more than any other preference is genetic. The fact that I like strawberry ice cream better than mint chocolate chip despite both of my parents' diametric opposition to my position in the matter probably isn't evidence of a recessive trait manifesting.
But again, who knows? Not the leftist idealogues championing a science that is admittedly still inconclusive on the matter, and not the religious zealots basing their position on faith, which, by definition, is believing without having conclusive evidence of your belief.