Jessica Alba has no problem playing sex object on the silver screen, but in her private life the actress says she’s a “prude.”

“Sex is absolutely what helps sell this movie, which is fine with me,” the actress, 33, said in an interview in the current Entertainment Weekly. “I’m also playing a character when people are taking pictures of me. That’s what I do, but it is not who I am.”

Unlike the sirens she’s portrayed in movies like “Machete” and “Honey,” the mother of two is proud to have never used sex to get ahead in life.

“I never slept my way through Hollywood, so I never felt like I compromised,” she said. “Apparently people do it, I didn’t. I felt like I never compromised myself because I’m a prude. I don’t know. I grew up Catholic. In my head I’m always thinking, ‘Oh God, can my grandma see this?’ ”

Alba and husband Cash Warren have been married since 2008. Together they have two daughters, Honor Marie Warren, 5, and Haven Garner Warren, 2.

The actress’ next movie, “Frank Miller’s Sin City: A Dame to Kill For,” hits theaters on August 22.