Here's a question for Cain: Is being heterosexual also a choice? Because, although I'm heterosexual, I don't recall making it. All I recall is that I began to notice girls, have erections associated with such noticing, to have physically messy dreams, etc.
One thing I don't recall doing is sitting on a rock somewhere, assuming the pose of Rodin's "Thinker" and musing over the question, "Well, gee, do I want to be straight or gay? Let's see,. Let me consider my options. Oh yeah. Now I've got it. I'll be straight."
Consider the same hypothetical soliloquy on the part of someone choosing to be gay: "Let's see, do I want to be straight or gay? So, if I'm gay, I'll be in a a miniscule minority, which will make finding partners harder. I'll have to endure all kinds of social condemnation and ostracism. I'll even possibly be criminalized and may in certain countries, be tortured and put to death, just for who am, even if I don't act on it; and I'll risk having thugs beat the crap out of me and possibly kill me even if they only think I'm gay. On the other hand, if I'm straight, all these problems go away. So, let me see, since it's entirely my free-will choice, I'll be . . . let me see . . . Oh yeah, I choose to be gay."