16. Drew Barrymore
Drew Barrymore grew up like your cousins who live in the dodgy parts of the Appalachians. She started smoking cigs at nine, drank by 11, smoked marijuanna by 12, and snorted cocaine at 13. The only difference is she got to hang out with the stars at Studio 54 when she was a preteen. At 13, she was already in rehab, and at 14, a suicide attempt landed her back in it again. She's posed nude twice, at ages 17 and 19, and once flashed David Letterman.
Nowadays, her younger self wouldn't even recognize her. Barrymore is focusing on being a mom.