A recent scientific study discovered that the side on which each of your organs end up is determined by the movement of hair-like cilia while you’re still an embryo! During embryonic development, the cilia start to move in unison, and the cells whose cilia move to the left end up in organs on the left side of your body, while those that rotate to the right become the organs that fill the right side of your body. So people with situs inversus simply have cilia that move in opposite directions from the rest of the population. Watch the video below to learn more about situs inversus and how your organs are arranged. Featured photo credit: public domain via photos-public-domain.com