How old are the characters in gossip girl?

The show or books. I've never read the books, and only caught a few episodes of the shows, but if they're in high school then I'm shocked. The people on the show don't look OR act like high schoolers. Yeah there's sex and drama in high school but give me a break. They're acting like they're in their 20s! whats the deal

Ahmen brother.
But then again it's not different than when Dawson's creek was on, or 90210. The actors are all in their twenties and they are certainly don't act or dress like teenagers. It's part of the magic that is television I suppose.
Then again....kids with money, especially in new york city, are privy to a more adult world and all it comes with. I'm only speculating but there is a reason why you see most of the worlds over privileged youth on the news in some kind of trouble.

in real life there probably in their 20's, but on the show their supposed to be like 17 years old.

THey are scandalous "seniors" in high school