Keira Knightley Doesn't Like Showing Off Her Bum

Pint-sized superstar Keira Knightley has no qualms about stripping off on screen -- as long as no one can see her bum.

The Edge of Love actress -- who was recently named Hollywood's second highest paid actress by Forbes magazine -- says she's not shy when it comes to baring all -- but prefers to have a body double for cheeky shots of her derriere.

"I don't really have a problem going topless, but my bum is a different matter," she says. "I like to have a body double for that. Other than that I don't have any problem with my body."

Keira, 23, recently revealed that she discusses her sex life with her mother, playwright Sharman Macdonald.

She told Britain's Glamour magazine, "Mum and I would always talk about sex. She'd come up to my room, have me roll her cigarettes and then tell me I'd have to have one with her. "It's not the typical mother-daughter thing but we're extremely close.

"Mum's a bit mental in a good way. She's this chilled-out hippy mother. My house was always the one where my brother and his mates would be drinking when they shouldn't be."