Birthmarks are skin blemishes that are present at birth. Most birthmarks are harmless and disappear or fade over time. Some names for birthmarks are stork bites, port wine stains, and café au lait spots. The true cause of birthmarks is unknown, but there are many myths and theories about them. Some people who believe in reincarnation think that birthmarks are actually marks of death. According to the birthmark theory, a birthmark indicates where a person was burned, shot, or speared in a past life.