I personally know someone like that. She's currently raising a kid she gave birth to thanks to a donated egg and IVF. Chromosomes are useful for first order approximations, but biology is a glorious fucking mess that cares not for simple binaries.

I hope that the person you're responding to will be able to form a new opinion after seeing these very measured and thoughtful responses. I'm really pleased with how calmly the community is handling this particular comment.