Just came up with this in my sleep. Do you ever wonder where the "you" in "you" came from? The general definition has been theorized as stemming from genetics and environment, but the second category is really broad: is it just friends and family? Difficult/challenging experiences? What else is there? It sounds like a college admissions essay because it is - aside from your pedigree, the people you interact with (friends, family, lovers), your work, education, what else makes up who you are? How do we develop this identity? And the answer to that question is culture, and not just any culture but pop culture. The movies you watch, the songs you listen to, the books you read, the video games you play, the clothes you wear. And it's not just using this culture as archetypes, e.g. our ancestors making the Odyssey popular because particular characters like Achilles or Hector exemplified certain values or traits people wanted to (or were encouraged to) emulate. It's also how you interact with that culture - like loving zombie movies, hating certain rap lyrics, or having a fascination with Malcolm Gladwell books.
It's also what you put on your facebook/myspace page, and also what other people (namely your friends) put up ABOUT you on such social networks. In fact you could argue the most successful social networks will be the ones which have nothing to do with software (like facebook) or monetization (like myspace, to some degree with their $900M google deal), and not even with viral effects which enable fast growth and user engagement, but with helping you understand who you are and who other people are. To that end you might argue facebook has an edge, because after F8 becoming released and the ecosystem of FB apps proliferating, I would say I know more about my friends, and my friends know more about me, than they ever did before. But the important point is that interacting with facebook is primarily a passive activity - it's not necessarily culture producing but culture facilitating. It's an information transmission process which enables people to experience culture based on shared or divergent interests.
I mention all these points because as human culture becomes more advanced and we have more spare time, it seems unlikely we'll find the answer to our identity from enlisting in wars (which was a huge impact on the pre-boomer and boomer generations), through work (which at times seems so unfulfilling depending on your job), education (which tends to end post college or grad school), or other avenues, but really through the content we consume and create, because it's an active, reciprocal process. It becomes a safer, more easily recognized way to express and more importantly, understand one's self.
There's probably a book somewhere in this mess of prose, I just have to find it. Thoughts welcome.