This is a very interesting thread. i don't usually comment in off-topic forum discussions, but this one got me. My "day job" is as an anthropologist studying virtual worlds. The anthropological vocabulary used around the issue raised in the opening post has two key terms - "embodiment" and "habitus".
Habitus is a much more difficult term to explain simply. Habitus has to do with the way that outside forces determine how we are allowed to express ourselves through our bodies, and how our bodies determine our sense of self. There are plenty of movies around that use the body-swap motif for comic effect. But there are also real-life situations in which wearing different clothes,changing postures, gestures, etc. are critically important. For example, when i lived in another country I began to dress, walk, talk and so on like the people who were born there - more and more as time went on. To the extent that people from my own country did not recognize me as one of them and would try to talk to me in a "foreign" language that was awkward for them, and were shocked when I fell back into the habitus of my homeland - revealing me as "one of us". I say I changed habitus because my posture, gestures, tone of voice all changed, not just the switching speech back to my first language. But it's much deeper than that. How we walk and talk is affected profoundly by how we were indoctrinated by parents and others - from before we we were born in many cases. Our sense of self is being molded at the same time, by the same people, through the same experiences. Most of that indoctrination we are no longer aware of. We don't usually stop to think "who am I if i wear this shirt?" or "am I truly chewing this food as my innermost myself, or because this is how I was taught an -------- chews?" If innate posture, vocal expression, and a thousand other things I'm not aware of influence how I experience myself as being in the world, and those things were imposed on me by other people's sense of what the proper way for my body to be is, then to what extent is my body me? When my body is in some way an imposed constraint on myself over which I have no control is it still me? Or is my body a prosthetic I'm more or less permanently attached to?
No easy answers to those questions.