From my observation, in most cases it is not a choice. I know someone who was Christian who thought her same-sex attractions were sinful, who fought against them for years, who wept over them and prayed constantly that God would take these feelings away. It would have been so much easier to choose heterosexuality and get the white wedding, handsome husband, little house with a picket fence, two kids, and a dog. I see no conceivable reason why someone would choose a sexual orientation that resulted in such personal suffering (due to her and her family’s religious beliefs) and rejection by others (due to theirs). Moreover, this woman has never had a girlfriend, so she’s certainly not chosen this orientation for licentious pleasure.
I can’t say that I chose to be heterosexual, either. I just started being interested in boys when I hit puberty. I’m sure some people are mentally flexible enough that they can be interested in either sex, but most are just hard-wired to prefer one or the other. There’s not much they can do about it.
I can only say that I believe in Gods plan and his plan was male and female. Its the only one that makes any sense.