At some point, you’ve probably wondered what the rarest eye color is. The answer is green, according to the American Academy of Ophthalmology (AAO). Only about 2 percent of the world’s population sport this shade.
As to why, that answer isn’t so simple. “We used to think only one gene determined eye color,” says Julie Kaplan, M.D., a physician at the Center for Personalized Genetic Healthcare at the Cleveland Clinic. In high school biology class, for example, you probably learned that brown was dominant and blue was recessive, so two blue-eyed parents would not be able to have a baby with brown eyes. The truth, however, is a bit more complicated, Kaplan notes.
What determines your eye color?
About 75 percent of eye color is due to one gene, OCA2. It makes melanin, a substance in your body that produces hair, eye and skin pigmentation. If you inherit two nonfunctional copies of the OCA2 gene from your parents, you will go on to develop blue eyes. But if you have at least one functional copy, your eyes will be darker, on the spectrum of green, hazel or brown.
Eye Color in the U.S.
The American Academy of Ophthalmology surveyed more than 2,000 Americans to determine what color eyes they have. Below are the results of that 2014 Harris Poll survey.
- 45 percent had brown eyes
- 27 percent had blue eyes
- 18 percent had hazel eyes
- 9 percent had green eyes
- 1 percent had eyes a color not listed above
Note: Survey weighted to reflect the United States population at that time.
In case you were planning to decorate your impending grandbaby’s nursery to match the color of their eyes, be prepared to be disappointed. It is impossible to predict what color their orbs will be. “There are several different genes involved, which we’re just beginning to learn about and understand,” Kaplan explains. HERC2, for example, is a gene that turns the OCA2 gene on or off as needed. Different variations of it can cause the OCA2 gene to produce less melanin, which leads to lighter-colored eyes. There are at least eight other genes that influence eye color. In the meantime, you can take comfort in the fact that your own individual eye color is like your fingerprints: something that is unique only to you.