Well, first of all The Color Purple falls under the broadest genre of fiction. The three primary genres are poetry, drama, and fiction.
Hair color is determined by two different forms of pigment: eumelanin (which is the largest influence) and phenomelanin. Eumelanin is a black pigment, and phenomelanin is a red or yellow pigment. Hair color is determined by three factors having to do with pigments: how much pigment is present, to what degree a eumelanin or phenomelanin is present and how close together the melanin (pigment) granules are. The more eumelanin a person has, the darker his hair will be.
Conclusion. 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.