Mary Kate Olsen and Ashley Olsen sign their new book 'Influence' at Barnes & Noble. New York City, USA - 28.10.08

The 22-year-olds began filming their first starring roles in U.S. TV series Full House at nine-months-old before launching a media empire with the start of their company Dualstar in 1993.

Ashley says, "There's a very specific language with financing and things like that. We definitely have a different perspective on running a business."

The pair was ranked among the world's richest women in entertainment, earning an estimated $100 million (GBP63.7 million) last year (07), according to Forbes magazine.

Source: WENN