Although the lives of celebrities are certainly in the public eye, there are a few personal things about famous actors that are virtually unknown to the general public—including who they've shared a womb with.

1. Scarlett Johansson

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Scarlett Johansson has a twin brother named Hunter Johansson, who was a campaign advisor for Barack Obama in 2008. While Hunter didn’t pursue a career in acting like his sister, the twins appeared together in the film Manny & Lo in 1996.

2. Vin Diesel

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While Vin Diesel (whose real name is Mark Sinclair Vincent) is enjoying a career in front of the camera with starring roles in action films such as Fast & Furious and Riddick, his fraternal twin brother Paul Vincent likes his place behind the camera as a film editor.

3. Ashton Kutcher

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Ashton Kutcher was born Christopher Ashton Kutcher, and has a fraternal twin brother named Michael. When he was a child, Michael developed cerebral palsy and cardiomyopathy and required a heart transplant during his teenage years. Before starring in That '70s Show, Ashton attended the University of Iowa and studied biochemical engineering, inspired to find a cure for Michael’s heart disease. Michael is currently a spokesman for Reaching for the Stars, an organization advocating for children with cerebral palsy.

4. Kiefer Sutherland

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Kiefer Sutherland was born the older brother of his twin sister Rachel. While Kiefer Sutherland is mostly known for starring as Jack Bauer on Fox’s thriller 24, Rachel works behind the scenes as a post-production supervisor on films and television in Toronto.

5. Giovanni Ribisi

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Giovanni Ribisi's twin sister Marissa had a budding career as an actress in Hollywood with roles in The Brady Bunch Movie, Pleasantville, and Dazed and Confused. She took a hiatus in the early 2000s, and married singer/songwriter Beck in 2004. Marissa Ribisi and Beck have two children, Cosimo Henri and Tuesday. Marissa also launched a fashion line called Whitley Kros in 2007.

6. Linda Hamilton

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Leslie Hamilton Gearren is the identical twin sister of actress Linda Hamilton. Although Leslie is a professional nurse, she was also her sister Linda’s on-screen double in three scenes in Terminator 2: Judgment Day.

7. Parker Posey

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Parker Posey was dubbed “Queen of the Indies” in the '90s for her appearances in movies such as Dazed and Confused, Party Girl, and Waiting For Guffman. Her twin brother Christopher took an alternative career route as a lawyer in Atlanta, Georgia.

8. Joseph Fiennes

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Joseph Fiennes has five biological siblings who took all up careers in the arts. His older brother Ralph Fiennes is an Academy Award-nominated actor, while his other brother Magnus is a composer, and his sisters Martha and Sophie are filmmakers. Joseph also has a twin brother named Jacob, who opted not to go into the entertainment industry, but instead started a career as a conservationist.

9. Eva Green

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French model and actress Eva Green’s breakout role was in the James Bond film Casino Royale. She has since appeared in Dark Shadows, 300: Rise of an Empire, and the upcoming Sin City: A Dame to Kill For. Green’s fraternal twin sister Joy took up a career rearing horses in the Normandy countryside with her husband.

10. Jon Heder

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While Jon Heder is mostly known for playing the titular role in the cult classic Napoleon Dynamite, his identical twin brother Dan Heder works behind the scenes in animation and visual effects, notably for the movie 47 Ronin. The brothers both worked on the Oscar-nominated animated film Monster House in 2006—Jon provided the voice for the character Reginald "Skull" Skulinski, while Dan was one of the film’s animators.