Sounds to me like you went different ways, weren’t together all the time, and each of you made different choices. That is how I define individual behavior and affected by environment.
That’s the thing, though. I never made a choice to be straight. It never occurred to me that hey, I need to make a choice whether to be gay or straight, just like for him, he never thought, no, I don’t want to be straight, I want to be gay.
Being gay for him was hard and he took a lot of shit for it, even before he told anyone. He didn’t act gay or talk a certain way, but people could tell. I could tell years before he came out to my parents and me.
But he never crushed on girls when he was younger. He always crushed on boys. I never crushed on a boy, I’ve never had a gay experience. But I never made that choice. That was just the default. Same as being gay was his default.