This is a romance book. Red hair occurs naturally on approximately 1–2% of the human population. It occurs more frequently (2–6%) in people of northern or western European ancestry, and less frequently in other populations. Red hair appears in people with two copies of a recessive gene on chromosome 16 which causes a mutation in the MC1R protein. Red hair varies from a deep burgundy through burnt orange to bright copper. It is characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment eumelanin. The term redhead has been in use since at least 1510. It is associated with fair skin color, lighter eye colors (gray, blue, green, and hazel), freckles, and sensitivity to ultraviolet light. Cultural reactions have varied from ridicule to admiration; many common stereotypes exist regarding redheads and they are often portrayed as fiery-tempered.