I've not had nearly enough coffee to get my head around @
0-markymark-0's comment, but on the topic of choice, for me, the only choices I make about my gender and sexuality are the same choices that everyone makes, whether they're male, female, straight, gay, bi, from the little choices about clothing/fashion to the ones about whether to respond in the affirmative if asked out, etc.
I did spend most of my childhood wishing I was a boy but as I grew older, I realised that was actually about how little girls were treated and expected to behave - I wanted the right to wear shorts/trousers to school, to play with cars and diggers and climb trees and do all the exciting things that my boy friends did. Aside from periods and risking a black eye whenever I run, I'm happy as a woman. And when it comes to sex, at no point have ever, ever wished I had a penis. So when it comes to my gender, there is no choice for me, just like there's no choice for any of us. I'm just lucky to be in the vast majority whose sense of self fits into the body it was born with.
Despite some rather cruel comments made when I came out, being a lesbian has nothing to do with my parents or my childhood or my preference for climbing (and falling out of) trees. It just is. I've got blue eyes, ridiculously little hands and am sexually attracted to women. I chose to come out, to live my life being honest, but it's not a lifestyle. I know women and men who got married and had kids when they were younger because that's what they were expected to do, and only admitted (or discovered) the truth (for want of a better description) when they were in their 50s or later. I know others who have never slept with a person of the opposite gender.
And whenever I'm asked about that, my answer is simple. How do YOU know your sexual preferences?
HTH