Literally every nonbinary person I know (with the exception of a tiny number of people who also happen to be intersex) and everyone that I know that knows a non-binary person or has done the slightest bit of research into the issue, is well aware that being non-binary is not a matter of chromosomes but rather a matter of gender roles.
Were you genuinely unaware of this, or did you have some different goal in asking this question?
I feel like I may be downvoted, but it's hard for me not to read your question as trolling (and if so it's working; see sibling responses). If I am wrong I apologize.
Ah, so they're still male and female, but we've added a dumber new aged twist on tomboys and sissies. Got it.
Alternatively, go read that short story by Isabel Fall.