I frequently chide a friend of mine--very much a cultural historian, but she's also only 22, and that disparity shows up in wide and wild areas. The one she lives with is all of 24, and while he catches a lot of my media references, many just slide right by him while he sits there, blinking, wondering if he should say something in return.

I think it's just something that happens around the time you realize that the stuph you listened to in high school is now played on VH-1 Classic, and to everyone but you, it's two decades plus back. Hells, for most of the people I virtually hang with on LJ, Nirvana happened too far back for them to remember.