By Paul Chi
November 07, 2011 12:00 PM

Playing a cult escapee in Martha Marcy May Marlene, Elizabeth Olsen tackles an edgy subject and bold nude scenes. Does her family-including famous sisters Mary-Kate and Ashley-approve? “They’ve always been supportive,” says Olsen, 22, who’s known as Lizzie to friends. “I’ve been making my family go to [shows] of mine since I was 8, and I feel bad about it now because there were ridiculous amounts of bad performances.”

The practice paid off. Olsen-who’s an NYU theater major-was the toast of the Sundance Film Festival and is now earning Oscar buzz for her big-screen debut. “She can be emotional without saying a word,” says [Martha] director Sean Durkin. The L.A. native grew up watching Mary-Kate and Ashley, 25, on the Full House set, but credits brother Trent, 27, a screenwriter, with inspiring her to act: “He’s like an encyclopedia of movies.” Still, “my sisters give me advice all the time,” says the budding star, who also has two half siblings. (Her parents divorced when she was 6 and her dad remarried.) “We love talking about films, fashion and even about guys.”

The Oscar talk is harder to take in. “When I was little, I’d pretend to be accepting awards for doing a movie with Frank Sinatra,” she says, “so with all this stuff, I can’t think about any of it being real.”