Everything You Know About Eye Color & Genetics is Wrong

Many of us were taught that two blue-eyed parents can’t produce a brown-eyed child. The laws of genetics simply forbade it, as blue eyes were thought to be a recessive trait that only occurred in the absence of alleles for brown eyes.

We were shown charts explaining how these genes did battle in a sort of microscopic “hand-paper-scissors” game played during gestation. However, this theory crumbled when scientists realized that blue-eyed parents WERE having brown-eyed children – albeit rarely. What was going on?

While certain eye colors appear more frequently among family members, it was difficult to pin-down any hard-and-fast rules. It turns out that the link between eye color and genetics is much more complicated than originally thought. Here’s what we know about how genetics influences the color of our eyes.

Geneticists now believe that there are two genes that play an outsized role in determining eye color, OCA2 and HERC2. The first gene influences the production of melanin, the pigment that gives color to our skin and irises. HERC2 can amplify or suppress OCA2, resulting in more or less pigment. If you have brown eyes, OCA2 is active. If you have blue eyes, it’s less influential.

This model isn’t nearly as satisfying as the dueling alleles, and it leaves a lot of grey area (coincidentally, another possible eye color). However, it goes a long way to explaining the connection between eye and skin color. People with black skin usually have brown eyes. While dark eyes are common in people with light skin, blue and green are almost exclusively found in those of European descent.

While complicated interactions among genes determine eye color, we now have the option of wearing colored contacts to change our look. If you’re considering this, be sure to get a prescription from an eye doctor; it’s the only way to ensure the products meet health and safety requirements.