He's not asking about gender, he's asking about sex. I don't know why he's getting so much flack for it.
Not like most people even check which chromosomes people have.
Just because you don't feel something, doesn't mean you can dismiss the mindset of others. Many people feel and demonstrate that gender is separate from sex and can be very much non-binary. It surely exists, whether you like it or not.
poof
Whoa, my bank account balance... it's true!
Thanks, stranger. Want some of my new money?
But I'm pretty lonely in that opinion.