This is a genuine question, and one that I have asked the forums before. But I have gotten older and so have the forums, so I want to pose the question again.
Are you what you produce? (ie, your profession?) What if you get laid off, or just retire early? If you produce nothing, does that mean you're worthless as a human being? Are you a human being or a human doing? What if you are disabled, mentally or physically, and it is a struggle for you to simply be independent? Isn't that worth something?
Are you what you consume? We are here, on Penny-Arcade, by virtue of being geeks: by that I mean that 'geeks' consume geek culture - comic books, video games, role-playing games, etc. And I realized that I do somewhat define myself by what I consume; my music collection, my book collection, my movie collection, etc. are all reflections upon me. That is unsatisfying to me, in a Fight-Club-esque way. To paraphrase and conflate a few separate but related passages: you are not your sofa, you are not your bedspread, you are not your clever Ikea table.
Are you how you act? Action is determined by situation - in a different situation I might act differently.
What you say? Speech is a negotiation between speaker and audience - my speech is determined as much by who is listening as what I'm thinking.
What you think? Thought is a sandbox in which open possibilities reign. None of these things define me.
Some people define themselves by their group membership: black or white, Pinoy or Vietnamese, gay or straight, male or female, Catholic or Protestant, Democrat or Republican, Giants fan or Dodgers fan. Hell, in my town, some people define themselves by what neighborhood they live in (as if they think that I don't know that they jumped on the first reasonably-priced apartment that offered them a vacancy).
Thus I pose the question to each forumer: what defines you? If God, a space alien, your therapist, your one true love, or the hypothetical proxy of your choice, asked you, "Who are you?" What would you say?
In other words, who do you think you are?
And since it's been three years since I last asked this question of the forums: how do you think that self-identification has changed?