Red hair is usually the result of a mutation in a gene called MC1R, also known as a melanocortin 1 receptor. Normally, when activated by a certain hormone, MC1R sparks a series of signals that leads to the production of brown or black pigment. Yet, in cases when both parents are carriers of the recessive MC1R gene and said receptor is mutated or antagonized, it fails to turn hair darker, resulting instead in a beautifully fiery buildup of red pigment.
As previously estimated by BBC News, between one and two percent of the world's population -- or 70 to 140 million people -- are redheads. In Scotland and Ireland, around 35 percent of the population carry the recessive gene that yields crimson locks, and the redhead count is around 10 percent. As such, the word ginger often calls to mind visions of Celtic-Germanic attributes -- namely, pale, white skin.
