Though we cannot deny the physical embodiment of gender, I believe that most of the idea of gender is psychological. Gender therefore has two separate parts. And though both parts interrelate, they do not necessarily cause each other. I can be born female but identify with more "masculine" things. Like tusayan said, what one culture defines as feminine or masculine another might not. So those terms are cultural and not definitive.
I personally tend to think more like guys do. I get along better with males, and they seem to understand me better than females, which makes me believe that I must think more like males than females. But I can't REALLY say for sure, since I've only been inside my mind. The point I'm making is that perhaps I identify more easily with males because I've spent more time with them. If I could restart my life and only be around females, perhaps I would identify with them more...if transgendered, maybe them...if homosexual or bi or any other type of group imaginable, maybe I would identify more with them.
I wonder whether we identify out of a certain level of comfort: "I have spent most of my time around __________(insert group here) so I understand them more; having that understanding makes me understand them in turn, which brings about a closeness I don't feel toward any other group. Therefore, I identify best with ________."
I don't think this an absolute...everything in the world has exceptions. But I wonder how often it occurs that we identify with a group, attributing it to 'who we are' when actually the connection might be best explained by how much we have invested in that identification, rather than the connection being inherent based on attributes we are born with.
What do you guys think?