In Your Eyes - Magruder Eye Institute

In Your Eyes

So summer is coming to an end, and school is getting ready to kick back into session. I thought I’d give you a little lesson to get your brain rolling. Today, class, we will be talking about the color of the human eye! What makes up the color of our iris? What determines this color? Can we predict our offspring’s eye color? These are all wonderful questions!

Melanin is responsible for the color of our eyes. When babies are born, most of the time they have little to no melanin, so their eyes appear blue. However, as they get older they develop melanin and their eyes turn to their natural color. So why do some eyes stay blue forever and others turn brown 6 months from birth? It’s all in our genes. Our genes determine the amount of melanin in our eyes. In school, you were probably taught eye color was a single gene trait. Modern science has determined otherwise, it is a multi-gene trait. There are two genes responsible for eye color, OCA2 and HERC2. The OCA2 gene controls ¾ of the blue/brown spectrum and HERC2 determines the expression of the OCA2 gene. Have I lost you yet? What about green eyes, how do they come into play? Green eyes are determined from the gey gene. This chart outlines the different combinations of eye color that parents can hand down to their offspring. Variation of the color is attributed to the Lyst gene, DSCR9 gene, and 17q25.3 gene. The rarest eye color is thought to be green, other than albino eye color and heterochromia eye color. Scientists are learning new information about the makeup of our eyes every day. Eye color is very interesting because it’s not cut and dry, multiple genes and genome combinations make up eye color. Our eyes are the window to our souls, so it’s fun to learn about what they are made of!

HERC2 Gey Eye Color
BB GG Brown
BB Gb Brown
BB bb Brown
Bb GG Brown
Bb Gb Brown
Bb bb Brown
bb GG Green
bb Gb Green
bb bb Blue

Brown: B Green: G
Blue: b Blue: b