Contortionist Sofie Dossi is back! Returning to the America's Got Talent stage to compete on the new Champions spinoff, the 17-year-old gymnast first made a name for herself on the show in 2016 for doing all sorts of dangerous acts while bending her body in super-human ways. So, how does she do it? Does Sofie Dossi even have a spine?! While the answer to the second question is obviously "yes," the reason she's able to pose like a human pretzel is a bit more complicated. According to Dr. Charla Fischer, M.D., an orthopedic surgeon at New York University Langone's Spine Center, some people really are just born with it — "it" being more elastic ligaments, joint capsules, tendons, and various muscles. Given that Sofie is a self-taught contortionist who began performing within a year of picking up the art, it's safe to assume that she falls into this category. "In general, people who are really flexible have loose joints," Dr. Fischer explains. "The joints are in tact, the spine is in tact, they're just able to exceed the normal ranges of motion." While there are certain conditions that make some people more bendy than others (connective tissue disorders, for example), Dr. Fischer says you don't necessarily have to have a medical issue to be really flexible.