Intersex people have been trying to publicize this shit for years, not to mention everyone outside of the gender binary.
Allow me to Introduce you to Androgen Insensitivity Syndrome. Simplified, these are people who can't process tesosterone properly. This means that someone Genetically XY can develop like this:
That's Eden Atwood, BTW.
There are even documented cases of XY women carrying children to term. Here's a good one.
I love to pull this shit out when people say "why can't we just assign bathrooms by chromosomes!?" as if it would fix the problem of Trans people and restrooms (specifically people thinking that men will dress as women just to get into a girls bathroom and rape people. News flash, by the way, they don't even bother with the dress, so leave trans women alone, we just want to go pee.)