Well, actually, it's more likely to be "not a choice" than "being a choice".

As far as I found when looking at Pubmed and Google Scholar quickly (25 min, maybe not the most thorough research), the general consensus seems to be a complex combination of nature and nurture during pre-natal development and the first years of life. It is not something you can really change (hence, also, the failure of "gay conversion therapy")

"It is not something you can really change"

Oh wow, so it is something that can change. I mean, people's sexuality does change. There are cases of people changing their sexuality later in their life. if we accept sexuality as something fluid then it wouldn't be impossible to say it couldn't change.

Even then, the fuck do you mean by nurture? What in someone's environment could turn them homo? Their food? The people they hang around? LOL

As I already said in my original point. Just because someone refuses to change something about themselves does not mean, it's not a choice or that it's genetic. Even if there is no "gay conversion therapy", this doesn't mean it's not a choice.