Myths of Human Genetics: Hair Color | "Red hair color is not an example of a simple genetic trait. While the amount of red pigment may be mainly determined by one gene (MC1R), there are a large number of different MC1R alleles, and other genes affecting the amount of brown pigment that plays a major role in determining hair color. The complicated genetics means that it is possible for two red-haired parents to have non-red-haired children."
If you have Scottish and/or Irish ancestry AND red hair, you probably also have VIKING ancestry, according to a new study. The director for Nordic Studies at the University of the Highlands and Islands says red hair is modern evidence of the influence of the ancient Vikings in Celtic lands.