Have you ever wondered why your eyes are the colors they are, or why some people’s eyes are a mixture of green and brown (hazel)? Even though we were taught how to draw those Punnett square diagrams in elementary school, there are many factors that contribute to the hue of your irises other than dominant and recessive traits.
To some extent, eye color is hereditary, and the appearance of parents’ eyes can be used to predict their child’s eye color. However, the HudsonAlpha Institute for Biotechnology has found at least eight different genes which control eye color, as opposed to the one allele which most students are taught to consider.
The biggest contributor to your eye’s shade is the same substance which creates your skin color. Melanin, an amino acid which determines how dark our skin appears, also develops the tint of our eye color as we age. In fact, most of us were born with blue eyes, and those of us with brown eyes simply developed more melanin in the front layer of our irises than everyone else. If you have green or hazel eyes, you have more melanin in this front layer than people with blue eyes, but less than those with brown.
Very little research has been conducted to determine eye color distribution around the world. However, in 2014, the American Academy of Ophthalmology distributed a Harris Poll survey which suggests the distribution of eye colors in the world as follows:
A little less than half of us have brown eyes
About 27% have blue eyes
About 18% have hazel eyes
And about 8% have green eyes.
Your eye color can change for the rest of your life as you age, and even throughout the day due to influences such as your emotions and the light of your surrounding environment. However, these changes are pretty subtle and require keen observational skills to notice. If you ever see a drastic change in your eye color, we recommend calling your eye doctor—this could be a sign of an underlying disease or other condition which needs treatment.
If you are healthy and want to monitor your vision changes, EyeQue has most affordable and convenient solutions. The EyeQue Insight can screen for 20/20 in about a minute; use it to track your family’s vision and verify if your glasses or contact lenses are up to date. The EyeQue Personal Vision Tracker can screen for refractive error (nearsightedness, farsightedness, and astigmatism) and help you order glasses online.
What other questions do you have about your eye color? Comment below, or send us an email!