POLL: Identity. Who are you, and what makes you... you?

Ok, this can get deep so pull your trousers up and take off your shoes.

I'm asking what everyone uses to define themselves.

As some of you may or may not know, the identity of the self is constantly shifting thanks to those around us and how we see ourselves (and they themselves) in them.

Without other people in the world, we would be unable to distinguish our own identity just as without "up" and "down" we would have no navigational orientation.

So; what are the most defining things to you that make up who you are?

Also, how do you express who you are?