where to start research on female biology?

[Xtempo]

I am writing something that takes place in the near future. So with the ability to change your gender with re-assignment surgery is there anything to actually test if a female was born a female and could whatever it is be forged?

So where the hell do I start? I know nothing of what actually defines and separates us other than having both XX chromosomes and lady parts which I do not have so I don't really understand there whole thing nor I don't know where to start.

I recall a big uproar over having a test if women were truly women a long time ago. It had something to do with the Olympic games. Did they established a test then?

I had no idea where to start so if you have any ideas or where to direct me that would be awesome! thank you

some of the story [I only write sci-fi/fantasy]:
A mother wants to keep her son because after a few months from the time of birth all boys are sent away never to really interact with females again except for sex. so the mother wants to prove he was born a she instead in order to keep him.