In a nod to her family, she wore a dress from The Row, a collection designed by her siblings Mary Kate and Ashley, who are 24.

She stars alongside Hugh Dancy, John Hawkes, Sarah Paulson and Brady Corbet in the film, which is about a young woman who escapes from a cult.

Sister act: Elizabeth Olsen at the screening of Martha Marcy May Marlene in Cannes last night

She has previously received strong reviews for her role, with the Daily Mail’s Baz Bamigboye noting in January: ‘She’s terrific, she knows when to be quiet and still, and can act without waving her arms all over the place.’

Elizabeth, who was chosen by Gossip Girl star Chace Crawford as one of his faces to watch in 2011, has come to the spotlight relatively late, instead honing her craft in the theatre, as an understudy both on and off Broadway.

She recently said she wanted to ‘let the professional acting wait until I felt confident and comfortable.’

In the spotlight: The 21-year-old with director Sean Durkin and co-stars Brady Corbet and Louisa Krause

It was, of course, a rather different story for her sisters, who were just toddlers when they landed roles in the hit sitcom Full House.

Mary-Kate, who battle with anorexia during her teens, once said she felt like they were ‘little monkey performers’ during their childhood.

Elizabeth’s next project is psychological thriller Red Lights, with Robert De Niro, Sigourney Weaver and Cillian Murphy.

The Olsen twins, whose parents divorced in 1995, also have an older brother, Trent, two younger half-siblings, Taylor and Jake.

Famous family: Ashley and Mary-Kate Olsen are household names with a billion dollar business empire