There are exceptions to the rule though, like women with AIS and XY chromosomes. I wouldn't call somebody with AIS a guy, because even if they have testes, I don't think they function . There's some with out any gonads, and ones with a complete female reproductive system.

"All of us were female in the womb until differentiation."
This is not true. If anything we were more hermaphroditic if you want to be pedantic, with both sets of ducts forming. The Wolfian and Mullerian ducts. I'm tired of keep hearing people saying this thinking it makes them seem smart or shocking. And maybe I sound crazy but this seems like something being said to feminize men.

Just so you know I'm a woman.