It's not a choice, that's obvious. And if if it was, how is it immoral to act on it?
Personally, my theory on homosexuality is simple. We all have both male and female hormones in our bodies on some level. I think gays might just have too much of the hormone from the opposite sex. That's not something that can be cured, it's just like having a birthmark, or being naturally intellectual, it's just who you are. No one should ever have to feel guilty for being gay. Unfortunately, we have the Church to do that to people, like they're pissing off God by being gay, and letting everybody down. It's all absurd.
If its hormones they can easily be regulated and lowered or raised. Hormone therapy is rather common actually.