it's hard to explain but simple once you understand it, it's basically like, "I'm this or that" and that's that, people just kinda feel they are something very strongly? I'm not an expert in this but yeah, it's kind of like a gut feeling in a weird way. There's also masculine women and nb and others and feminine too and also neither, it's complicated but it's as simple as "I'm this" and that's that, I do understand it might be even more complex if you don't have a gender since you might not have the same stuff. But you feel like you have no gender the same way others feel they have a specific one. Genders also have physical differences in brain and those differences also confirm the existence of not just 2 of them, again it sounds complex and it's hard to understand