Myths of Human Genetics

[RickHolland]

Red hair color: The myth

Some people have red hair, and some have hair that is various shades of blond or brown. The myth is that red hair is determined by a single gene, with the allele for red being recessive to alleles for other colors.

The reality

http://udel.edu/~mcdonald/mythredhair.html

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. The complicated genetics means that it is possible for two red-haired parents to have non-red-haired children.


Eye color: The myth

One of the oldest myths in human genetics is that having blue eyes is determined by a single gene, with the allele for blue eyes recessive to the allele for non-blue eyes (green, brown, or hazel). Many people who know nothing else about genetics think that two blue-eyed parents cannot have a brown-eyed child.

The reality

http://udel.edu/~mcdonald/mytheyecolor.html

Conclusion

Eye color is not an example of a simple genetic trait, and blue eyes are not determined by a recessive allele at one gene. Instead, eye color is determined by variation at several different genes and the interactions between them, and this makes it possible for two blue-eyed parents to have brown-eyed children.