20 Under 20: Celebrities You'd Be Surprised To Know Are So Young (PHOTOS)

03/14/2013 03:28 pm ET

There must be something about growing up in the public eye that accelerates the process. Otherwise, we're not sure how to explain the slew of high-profile celebrities who get treated like adults, want to be taken seriously like adults, and behave just like their grown-up counterparts, when they're not even allowed to legally drink yet.

Bieber's recent downward spiral made us realize that underneath all the money and the fans, the kid is only 19. So we went ahead and checked -- who else gets mistaken for being much older than they really are?

20 Under 20

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