Genetics of Red Hair
Red hair is mainly caused by variants in the MC1R gene. This gene affects how pigment cells produce melanin. People with certain MC1R variants produce more pheomelanin and less eumelanin, which gives hair a reddish color. Both parents must pass on the variant for a child to have red hair.
Role of Melanin
Melanin is the pigment that determines hair, skin, and eye color. Eumelanin creates brown and black tones, while pheomelanin creates red and yellow tones. In redheads, higher levels of pheomelanin lead to reddish hair. This also often results in fair skin and freckles.
Global Distribution
Red hair is most common in Northern and Western Europe, especially in Scotland and Ireland. Studies estimate that around 1 to 2 percent of the global population has red hair. For more details, see the genetics overview on the National Institutes of Health website.
