She’s her own twin

Taylor Muhl carries two sets of DNA – it’s akin to being two separate people. Muhl’s rare condition comes from her absorbing her fraternal twin in the womb. Known as chimerism, the phenomenon helps explain why Muhl is plagued by an autoimmune condition: She has two immune systems and two bloodstreams, and her body rejects her twin’s DNA as an invader. This has led to severe allergies her whole life; it also explains the unique birthmark that divides her abdomen at the midline, colouring the right side of her body. “I felt freedom [after the diagnosis] because for the first time in my life I knew why my stomach looks the way it does,” Muhl told People.
Her hero turned out to be her sister

Jen Bricker may not have had any legs when she was adopted as a young child from an orphanage in Romania, but she had more than enough spirit – so much so that she was drawn to gymnastics despite her disability. Her goal was to be like her idol, Olympic gold gymnast Dominique Moceanu. Bricker eventually turned that spirit into a career as an award-winning tumbler and aerialist. But her focus on Moceanu may have been more than gymnastics: In 2003, Bricker discovered that Moceanu was actually her biological sister. Her birth parents were both Olympic gymnasts. Since then, Bricker, Moceanu and a third sister, Christina, have all connected.
Being identical is more than skin deep

In 1979, when identical twins Jim Springer and Jim Lewis finally met at the age of 39, they didn’t just have the same first name: Their wives had the same name, and so did their childhood dogs. Coincidence? Perhaps, but that wasn’t all. They also shared tension headaches, a nail-biting habit, and an addiction to Salem cigarettes. Each drove Chevy’s and liked to frequent the same sandy beach in Florida.
“Genes can help explain why someone is gay or straight, religious or not, brainy or not, and even whether they’re likely to develop gum disease,” one psychologist explained to Live Science. (Both brothers were part of the Minnesota Twin Family Study, which studied 137 pairs of separated twins over a 20-year period.)
Check out more fascinating stories of twins separated at birth.