As the world's most famous twins celebrate their 30th birthday, we've tracked down some little-known facts about the duo – here are 10 things you might not know about Mary-Kate and Ashley Olsen...
1. The twins were cast for Full House at nine months after their mother's friend introduced her to an agent who asked to see their photographs. Their mother was reluctant for them to audition.
2. They were chosen out of 20 sets of twins to play the role of Michelle Tanner, and were said to have won the part because they were the only babies who didn't cry during the audition.
3. Despite their incredibly similar appearance, Mary-Kate and Ashley Olsen are non-identical twins. Ashley is two minutes older than Mary-Kate.
4. Mary-Kate and Ashley aren't the only entrepreneurs in the family – in primary school, their older brother James sold photographs autographed by his famous siblings to his schoolmates.
5. The twins missed their prom to host Saturday Night Live! in 2004. To help make up for it, guests Jimmy Fallon and Will Forte did a prom sketch especially for them.
6. You'll never see their belly buttons... ! "When we were growing up, our mother taught us never to have your belly button exposed," Mary-Kate once revealed.
7. Neither have Facebook or Twitter accounts. Mary-Kate once said of social media, "That gives me so much anxiety. We've spent our whole lives trying to not let people have that accessibility, so it would go against everything we've done in our lives to not be in the public."
8. Ashley's favourite smell is cinema popcorn while Mary-Kate's is coffee.
9. Mary-Kate's looks to Gigi Hadid for fashion inspiration. She told Vogue: "She always looks effortless and cool.
10. Mary-Kate is one inch taller than Ashley!