Watch: Mary-Kate & Ashley Olsen Make Rare Public Appearance at NYFW 2025Thirty-two years ago, Mary-Kate Olsen and Ashley Olsen brewed up Double, Double Toil and Trouble. By this time, the then 7-year-old twins were already the youngest self-made millionaires. After launching their careers at the ripe old age of 8 months with the shared role of Michelle Tanner on Full House, Mary-Kate and Ashley quickly grew their empire.