Why You Have the Eye Color You Do

GreeneyesWhy do people have different eye colors?
The iris of the eye gives it color. In the iris, there is a pigment which is dark brown called melanin. Melanin is produced to help the body protect itself from sunlight. If the amount of melanin in the iris is high, the eye color is brown or dark hazel. Lower amounts of melanin give green and blue eye color. People with lighter hair and skin have lower levels of melanin and usually have eyes with lighter color. Babies are born with blue eyes. Their eye color changes as they grow and begin to produce more melanin.
How is the amount of melanin determined for each person?
There is a coding process passed from parent to child called genes. Our genes are the building blocks that make each of us unique. At one time, it was believed that eye color was controlled by a single gene and inherited. Now we know the process is more involved. We believe that eye color is a trait controlled by several genes linked together(1.) and brown eye color is the dominate color.
Blue eyes
Interesting new research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a gene change which took place 6-10,000 years ago. This change is the cause of the eye color of all blue-eyed humans alive on the planet today. Professor Eiberg says “Originally, we all had brown eyes.”(2.)
Change your eye color
Sometimes adult eye color can change. It can be due to the light reflections of clothes and different environmental colors around them. Colored contact lenses can be fun way to change eye color if you want to enhance what you were born with. Be sure to visit your eye doctor for a proper fit and correction of colored contact lenses.


1. Fan Liu et al., “Digital quantification of human eye color highlights genetic association of three new loci,” PLoS Genetics 6 (2010): e1000934, http://www.ncbi.nlm.nih.gov/pubmed/20463881.

2. Hans Eiberg et al., “Blue eye color in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression,” Human Genetics 123, no. 2 (March 2008): 177-187, http://www.ncbi.nlm.nih.gov/pubmed/18172690.

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