Eye Color Genetics: Discover What Determines Your Eye Color

More than just mirrors of your soul, eyes are mirrors of your genetics and health, too. When it comes to eye color genetics, scientists have discovered that at least eight genes influence the final color of eyes. These genes control the amount of melanin inside specific cells of the iris. Some of the eye color genes include OCA2, which is one of the major pigmentation genes that affects the amount and quality of melanin in melanocytes and HERC2, which functions as an enhancer regulating OCA2 transcription.

In humans, the pigmentation of the iris changes from light brown to black, depending on the concentration of melanin in the iris pigment epithelium and within the iris stroma, and the cellular density of the stroma. According to Vision Direct, the most common eye color is brown, marking 80% of people all around the world. Whereas, approximately 8-10% of people in the world have blue eyes, 5% have amber or hazel eyes, and 2% of people have green eyes. But, did you know that blue, green, or any other eye color does not result from blue or green pigment? This because there is only one single type of pigment called melanin and it’s brown. Melanin is responsible not only for the color of human eyes, but also for the hair, and skin color. Specialized cells that produce melanin are named melanocytes. So, it’s the total amount of melanin in your iris what determines the range of your eye color; the highest amount of melanin is found in brown eyes, whereas the lowest amount is found in blue eyes.

Another reason for having blue, green, or hazel eye color, is the same as with water and the sky. They scatter light so that more blue light reflects back out, which is known as Tyndall scattering Effect of light in the stroma – a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering. So, your eye color varies depending on the lighting conditions, especially for lighter-colored eyes.

eye color genetics
Photo Credit: Amanda Dalbjörn on Unsplash

How does eye color genetics work?

Did you know that initially we all had brown eyes? According to Hans Eiberg, associate professor in the Department of Cellular and Molecular Medicine at the university and lead author of a study, “a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a ‘switch,’ which literally turned off the ability to produce brown eyes.” According to researchers at the University of Copenhagen, this genetic mutation occurred 6.000 to 10.000 year ago in a single individual in Europe. Therefore, it is concluded that all blue-eyed individuals have the same ancestor.

Moving on to the inherited genes, the moment you are conceived, you inherit one chromosome from each parent to make each pair of your chromosomes. Chromosomes carry all of the genetic material of an organism, from height to eye color. These genes tell a cell in the iris to produce specific amounts of the melanin. So, the more melanin it produces, the darker the eye color will be. Genes which bring higher levels of pigment and result in brown eyes are dominant over genes which produce lower levels of melanin, which result in blue eyes. This means that if you inherit a brown eye gene, it will win out over a blue eye gene.

 

Can you predict the color of your child’s eyes?

Not always, a child will inherit his parents’ eye color. That’s because geneticists now have concluded that eye color is affected by 16 different genes to some degree, and not just one or two genes as it was once believed. Also, the anatomic structure of the iris can influence eye color to some degree.

Hence, it’s impossible to know for sure the color of your child’s eyes – even if you and your partner both have blue eyes, there is no guarantee your child’s eyes will also be blue.

eye color genetics
Photo Credit: SofieZborilova on Pixabay

Can your eye color change?

According to Vision Direct, melanin production does not begin at birth, which can cause babies’ eyes to appear blue. But, around the age of three, the eye color which is going to be permanent on a child’s eyes appears.

However, your eye color may also change with the lighting. That’s because the iris is created from two layers. Brown eyed people have both layers pigmented, whereas blue or green-eyed people have small amounts of melanin in the front layer. So, depending on how much external light hits the eye, your eye color may change.

Light can also have an effect on the size of the pupil. The dimmer the light, the larger the pupil size, the brighter the light, the smaller the pupil. Therefore, when the pupil size changes, the color in the iris may slightly change too.

Sometimes, the eye color, same as your skin color, may change under the effect of sun exposure.

The fastest way, however, to change your eye color, is by wearing colored contact lenses. So, if you’re willing to try a new color, go visit Europe’s largest online contact lenses, Vision Direct.

eye color genetics
Photo Credit: Patrick Brinksma on Unsplash

 

See also: 

How To Put In Contact Lenses In A Few Easy Steps

How To Remove Contact Lenses: Step-By-Step Guide