If one of these changes is present on both chromosomes then the respective individual is likely to have red hair.This type of inheritance is described as an autosomal recessive mode of inheritance.Cultural reactions have varied from ridicule to admiration; many common stereotypes exist regarding redheads and they are often portrayed as fiery-tempered.The term redhead has been in use since at least 1510.The lower melanin concentration in skin confers the advantage that a sufficient concentration of important Vitamin D can be produced under low light conditions.However, when UV-radiation is strong (as in regions close to the equator) the lower concentration of melanin leads to several medical disadvantages, such as a higher risk of skin cancer.
However, a How Stuff Works article says that the foundation was funded by hair-dye maker Procter & Gamble, and that other experts had dismissed the research as either lacking in evidence or simply bogus.
In the United States, it is estimated that 2–6% of the population has red hair. In Asia, red hair has been found among the ancient Tocharians, who occupied the Tarim Basin in what is now the northwesternmost province of China.
Caucasian Tarim mummies have been found with red hair dating to the 2nd millennium BC.
Red hair appears most commonly in people with two copies of a recessive allele on chromosome 16 which produces an altered version of the MC1R protein.
Red hair varies in hues from a deep burgundy or bright copper (reddish-brown or auburn) through to burnt orange or red-orange and strawberry blond.
The genetics of red hair, discovered in 1997, appear to be associated with the melanocortin-1 receptor (MC1R), which is found on chromosome 16.