Genetics and sun exposure are mostly to blame for moles, but they don’t appear to serve an inherent biological function. Still, history has rarely treated them as meaningless. Many cultures have assigned supernatural importance to moles, sometimes with fatal results. An ancient Greek text attributed to the philosopher Melampus describes how the location of moles affects a person’s fate (a man with one on his forehead, for example, is destined for wealth and happiness). During the Salem Witch Trials, accused parties were examined for blemishes because it was widely believed that moles and birthmarks signified ties to the devil.