You may struggle to tell them apart, but America's best-known twins aren't even identical! Fraternal twins Mary-Kate and Ashley Olsen (pictured in May 2012) got their start playing Michelle Tanner on Full House when they were just 6 months old. They turned their popularity into a mini empire of movies and television shows produced by their own company, Dualstar, and were millionaires by the age of 10. Currently, the twins run a number of fashion brands, including high-end line The Row and contemporary collection Elizabeth and James. Though Mary-Kate has also returned to acting, appearing in Weeds and Beastly, their twin connection is not affected by separation. As Ashley told Marie Clairein 2007, "Our bond is really beyond words. I know when she's hurting, I know when she's going through something. I know when she's happy -- whether I'm with her or not, I know."