Matt, I think you articulated your thoughts very well, and I find Articulated Kat's response frustrating.

One thing I will mention though, is that many trans people describe a feeling of their brain being "mis-matched" to their genitals. That is, their feeling stems from something more innate than just their socialized perception of what they think it should feel like to be a man or a woman.

I think, for the most part, brains are pretty moldable, and will basically adapt to - and identify with - whatever body / situation you put them in. But perhaps there is indeed a little bit of hardwiring that goes on such that people's brains can anticipate having, for instance, a vagina, when their body has a penis. And so they will say they are a woman on the inside, when on the outside, for all intents and purposes, they are a man.

I think, in the absense of some sort of brain mis-matching (for lack of a better word), then your theory probably holds, and the perception of a person knowing they are a man or a woman would basically come down to how tightly they are bound to their culture's gender myths. But given many trans people's accounts of how they feel about their genitals and bodies specifically, I think there is probably something more to the story than just a percieved mismatch of gender roles.