People who know me only casually often say they're impressed with my intelligence or something similar. But when I'm with family, I often feel like a moron (and they share the sentiment). The simple fact of the matter is that I often am.
I've noticed that my tone of voice changes with family. My voice becomes higher pitched, somewhat timid and submissive. On the other hand, if I'm hanging out with a bunch of guys on a back porch or in a bar, my voice naturally becomes deeper, my comments more assertive. This is nothing particular to me. It's similar with everybody.
Only the core of our personalities are hard-set. Who we are changes slightly from moment to moment depending on who we are around and what the situation is.
Our expressions change from group to group. We're silly and light-hearted around some people, serious and philosophical with others. In some groups we take leadership roles, in others we become followers. Our interests rise and fall with the settings.
Why don't we see this more in game characters?