Sexual orientation, at least for me, is not a choice.
There is a segment of society that is certain sexual orientation is a choice.
I have a hunch that some of those folks who profess "being gay is a choice" are themselves bisexual.
Why do I say this?
Those folks are a little bit too sure of themselves, as if they speak from personal experience.
How can that be?
If they desire both traditional and non-traditional relationships but made a concious choice not to pursue, for example, same-sex "gay" desires (at least not when anyone is looking) then they are able to frame being "gay" as a choice, a choice they did not make.
So perhaps they assume we all must somehow fit that model, where I ultimately chose to be sexual with men and they didn't.
I know the above is a generalization and not based on anything academic. It is based on me trying to piece together what I've experienced, friends that wanted to be sexual with me and even loved me but also loved women and ultimately married a woman and had a traditional family.