A rare genetic defect causes some people to be born with hair all over their bodies. Fewer than 100 cases of hypertrichosis, also known as “werewolf syndrome,” have been documented in scientific literature and media reports, geneticist Xue Zhang told New Scientist in 2009.
Fedor Jeftichew, better known as Jo-Jo the Dog-Faced Boy, had hypertrichosis and performed in a Russian sideshow, ca. 1880s. Charles Eisenmann
