Responses
It because of their mentality and surrounding. Homophobia exists in so many part, and I think in the universe the author had created, they're even more, seeing that a person can choose their own gender during their coming of age. It's that kind of "If I am female, I definitely wanted that person I like since childhood to be a man for me and build a family together" mentality. So, yeah (The way I explain this really sucks I'm sorry)
Like you know what, the "pick a gender cuz if not you'll die" is a valid loint, but wht they gotta be a girl for you? Or a guy? You would t date them if they're same-sex? Asshole?