And even without being a biologist, the question itself is incredibly complex to answer due to the evolution of language and the nature of gender norms (as the west defines them) in general. One can define X or Y based on their own expectations of X or Y, but what about someone else who's upbringing or Culture has different definitions of X and Y? What about cultures who go into the Z axis? It puts into perspective how absolutely arbitrary a lot of our definitions are yet there -is- a definition there somewhere.
I won't get too much further into it, because of forum rules and the fact that the topic is -so- broad and outside my usual wheel house that I couldn't even begin to do it justice. But the whole thing is quite fascinating.