Ever wonder why you were born with blue eyes? Or green or brown? It’s not random; rather, it has a lot to do with genetics. Sometimes, eye color changes, such as when a baby is born with blue eyes but after a few months fades to brown or green. Some people even have two different colored eyes.
There are two top factors that play a role in determining eye color: first, the pattern and amount of dark-brown pigment, called melanin, in your iris. The iris is responsible for scattering the light that goes through your eye. Second, pigment determined by your genes also plays a role.
Let’s go over a quick lesson in genetics. You have 46 chromosomes, divided up into 23 pairs. You inherit one chromosome (made up of DNA called genes) from each parent to make up a pair. These genes you receive determine lots of characteristics about you, from how tall you are to the color of your hair, and indeed even what color your eyes are.
The genes responsible for eye color are part of chromosome 15, referred to as OCA2 and HERC2. Genes are comprised of alleles that decide which characteristics will show up. For every trait you inherit, two alleles are present. Two like alleles are called homozygous. Two different alleles are called heterozygous.
For each trait, one allele is dominant and one is recessive, which means one appears and one doesn’t. Let’s look at the alleles for eye coloring. They can be separated into brown, green and blue:
Green dominates over blue.
Brown dominates over blue and green.
Those with blue eyes got blue alleles from both parents.
Your genes are also responsible for determining eye color by contributing a certain amount of melanin in the iris. The more melanin present, the darker your eyes will be. If you’ve ever wondered why many babies’ eyes are blue at birth but then change within a few months, it’s because the production of melanin doesn’t begin immediately at birth. True eye color won’t be determined until about the age of three.
Because your iris is comprised of two layers, sometimes your eyes may appear differently depending on the lighting or what color outfit you’re wearing. For those with green or blue eyes, the front layer doesn’t have much melanin, so when light is diffracted, the eyes may look like they’ve changed colors.
People with two different colored eyes have what’s called heterochromia, which is rare yet harmless. This condition occurs when the iris is first developing.
Contact Simon Eye Associates
No matter what color your eyes, the vision care professionals here at Simon Eye Associates are ready to help you keep them healthy. To learn more or to schedule an appointment, call Simon Eye Associates today at 302-239-1933 or complete our convenient online form. We offer annual eye exams to families in Wilmington, Newark, Bear, Middletown, and nearby DE areas.