Teen actress Mary-Kate Olsen's fixation with coffee began at an early age - she sneakily gulped down cups of the beverage when she was just 10 years old.

The petite 19-year-old, twin sister of actress ashley, is constantly photographed with cups of coffee in her hand whenever she's out and about, and she admits that the habit started early.

She says, "When I was younger, on weekends, my mom would make us pancakes with our initials on them and then a tiny cup of coffee.

"(By the time I was 10) I was sneaking my own and pouring a ton of sugar in and going up to the playroom and drinking it."