It's quite simple, really. I've never had to "choose not" to be a homosexual for the same reasons I've never had to "choose not" to be a rapist, or a child molestor, or engage in bestiality, or rob convenience stores, or kill people for money. It's because I find those pursuits to be morally repugnant and unnatural. If I wasn't guided by moral principles I could very easily choose any licentious behavior I wanted to seek satisfaction. I would become a pure stimulus-response creature who wouldn't care how my genitals were tickled as long as I reached orgasm.
Homosexuals lack that particular moral barrier just like rapists, necrophiliacs, child molestors, etc., lack their own. The only saving grace is that it generally occurs between two consenting adults, and because of that it is tolerated to a great degree. That's not enough for practitioners of homosexuality, though. They want it embraced, saluted, accepted as virtuous. That way, they don't have to dwell on their moral deficiencies or feel guilty.
