What Is the Most Common Eye Color?

Your eye color comes from pigmentation in the iris, which is a membrane that also controls the size of your pupil and allows light inside your eye. Inside the iris is a brown pigment called melanin that gives your eyes their color. The amount of melanin and how it is distributed determines your specific shade of color. Brown is the most common eye color in the world.

Close-up of brown eye

Leland Bobbe / Getty Images

Even people with blue or green eyes have some melanin in their eyes. They simply have a lot less melanin than someone with brown eyes. The iris has two layers, so people with lighter-colored eyes still have melanin in the back layer that is not visible. People with brown eyes have melanin in both layers of the iris.

Eye Color Percentages

Eye colors can range from pale blue to dark brown that looks black.

Brown is considered to be the most common eye color in the United States and the world. More than half of all people have brown eyes. Green eyes are considered to be the rarest, and only 2% of all people have them.

Eye colors in the United States fall into the following categories:

  • Brown eyes: 45%
  • Blue eyes: 27%
  • Hazel eyes: 18%
  • Green eyes: 9%
  • Other eye colors: 1%

People who have albinism may not have any pigment in their eyes, so their eye color may be red or pink. This happens because the iris is clear without melanin and allows the blood vessels to show through.

Genetics of Eye Color

Multiple genes help determine your eye color. Research shows that you cannot predict a baby's eye color based only on the parents' eyes because many genes are involved.

Genes affect how melanin is made, moved, and stored in your body. For example, a protein coded by a gene can influence how much pigment is created by melanosomes (cells that make melanin). If you produce less pigment, then you end up with blue or green eyes.

Genes that are involved in determining your eye color include: 

  • OCA2
  • HERC2
  • ASIP
  • IRF4 
  • SLC24A4
  • SLC24A5
  • SLC45A2
  • TPCN2
  • TYR
  • TYRP1

Why Brown Is Most Common

Researchers believe that brown eyes are the most common because our ancestors and first humans had this eye color. There is an advantage to having brown eyes in areas with a lot of sunlight since the melanin protects them.

Ancestors that came from Africa had brown eyes to guard them against the damaging ultraviolet rays.

Reasons for Other Eye Colors

Blue and other eye colors developed from a mutation (genetic change). A single ancestor probably had a mutation 6,000 to 10,000 years ago that affected melanin production and resulted in lighter-colored eyes.

Researchers believe that lighter eyes appeared once our ancestors left Africa and spread to Europe. These areas had less sunlight, which meant there was less of an advantage to having more melanin.

The reason why someone's eyes look green or blue has to do with the amount of melanin in the iris. When there is less pigment, there is less light that can be absorbed. The light is scattered and reflects. Eyes that have the smallest amount of melanin are blue. Eyes with more pigment will be green.   

Why a Baby’s Eye Color Changes and When It Is Permanently Set

Many babies are born with blue eyes, but they change color over time. The melanin increases in their eyes and can change them to brown or make them darker within 12 months. The buildup of pigment takes time to develop in babies.

By the time a child reaches the age of three, the eye color is usually set permanently. Often, this happens even faster for most children, and their eyes are set by nine months. An adult's eyes can change color because of:

  • Genetics
  • Trauma
  • Illness
  • Sun damage
  • Medications

Effect on Eye Health

People with some eye colors are more likely to experience different health conditions. For example, brown eyes are linked to a higher rate of cataracts compared to other eye colors. A person who has a brown eye color may be two times more likely to develop cataracts than someone with blue or green eyes. It is not clear why this is the case.

There are also advantages to having brown eyes, such as a lower risk of:

  • Macular degeneration
  • Diabetic retinopathy
  • Eye cancer

If you are concerned about your eye color or the overall health of your eyes, talk to your ophthalmologist and get an eye exam. 

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Article Sources
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  1. American Academy of Ophthalmology. Why are brown eyes most common? Updated April 7, 2017.

  2. American Academy of Ophthalmology. Eye color: Unique as a fingerprint. Updated December 5, 2017.

  3. American Academy of Ophthalmology. Your blue eyes aren’t really blue. Updated November 30, 2016.

  4. MedlinePlus. Is eye color determined by genetics? Updated September 18, 2020.

  5. American Academy of Ophthalmology. Why are my eyes changing color? Updated February 28, 2019.