Wednesday, April 3, 2019

Eye Color; Myths of Genetics

There are many myths regarding genetics and inheritable traits. Even when most of them have been clarified, people are still confused about some patterns of heredity. One of the most popular myths of genetics is eye color, specially those in the blue category since it is less common.
People used to believe that eye color were single genes, and that blue is a recessive allele of other non-blue eye colors like greens and browns. A research on myths of human genetics by John McDonald notes that eye color is not a simple hereditary trait, in fact there is at least 12 genes involved and phenotypes vary not only with the genes themselves but also with the interactions with each other.

Heterochromia: Different pigmentation/concentration of melanin.
Many articles explain that the coloration of the eyes is mainly based on the presence and absence of melanin, and that essentially there is only one eye color, brown; other colors are a product of reflection and absorption of light. Melanin is a brown pigment that absorbs light; in blue eyes, there is less melanin thus more light is reflected. For eye color, there are genes that determine the melanin's quality, quantity, dispersion, concentration, etc. Other factors like the amount of collagen in the iris and blood vessels can also affect the color expressed. Eye color is still believed to be genetic but is more complicated than simple dominant-recessive alleles.

1 comment:

  1. This eye color heredity is very interesting it happens because the OCA2 and HERC2 are close together. Since, both genes are close together they're inherited together.In people that are Albino there is much less pigment than other people and is why you can see the blood vessels in the weight's of their eyes. This research makes sense based on pigmentation of eye color. I think in the future people will manipulate there genes in order to have naturally occurring blue eyes.

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