And this is where it gets dicey - and, just to be clear, I have counterarguments to the case I'm about to make... But what things like this do is make it a discussion and not a simple "here is the fact" because there are all sorts of anomalies which muddy the waters on the clarity/primacy of that fact.
Ever heard of trisomy? It's where a person has three X chromosomes and not two. You know how, in the post above the one I'm responding to, you ask "Can an XY become an XX?" You seem to be leaning towards a biological basis for what you consider a woman/female to be, where a man has XY chromosomes and a woman has XX. Well, XXX isn't XX. Is a person who is XXX not a woman? Most will go through their whole lives being, functionally woman in every sense of the word but that bit of genetic coding. There is a good chance you have known an XXX person and thought "that's a woman" and you may have actually seen one with their baby hanging off their boob getting milk. Some info on it:
Triple X syndrome - Symptoms and causes - Mayo Clinic
Why this complicates things is because it makes a totally clear cut biological definition tough to pin down. Is it chromosomes? XX only? Well, if you just say that XXX people aren't women, then you commit to a position where a person who has given birth to a baby that they breastfed and hasn't ever had a lick of trouble "passing" as a woman isn't a woman. Is it tied to the ability to bear children? Breastfeeding? Having a womb? PMS'ing? You can niggle and find exceptions on any one of these points, and each and every one can be made to seem counterintuitive when someone say "Ah, but see this person here (who is clearly a woman) that shows your whole position to be inconsistent."
Personally, I recognize that there is a societal discourse on what a woman is. I draw a line at the point where people start to insist the term means something that just confuses the fuck out of the whole issue, where the discursive landscape tends to understand it quite well without the addition. People, right now, are just fucking things up.