Home / Science

What Is the Rarest Eye Color? Discover Why Only 2% of People Are Born With Them

By Emma Taggart on June 8, 2026

Closeup of a man with heterochromia - two different eye colors, one blue eye and one green eye

According to the American Academy of Ophthalmology, only around 2% of the world’s population has green eyes, making them the rarest eye color across the globe. But what actually creates those striking green irises?

Eye color is inherited through genetics, but it’s difficult to reliably predict what a child will end up with. That’s because multiple genes work together to determine pigmentation, and their interactions can vary widely from one person to another. Differences in how these genes are expressed can lead to a surprising range of outcomes, even within the same family.

No two people have exactly the same eye color (including identical twins), but until roughly 10,000 years ago, brown eyes were dominant across human populations. Scientists believe a spontaneous mutation affecting melanin production in the iris helped introduce the lighter eye colors seen today.

Although some eyes may appear blue or green, there are no blue or green pigments present. Instead, color variation comes entirely from the amount of melanin—or brown pigment—in the iris. Green eyes are created with a mix of lipochrome—a yellow, fat-soluble pigment also found in egg yolks and butter—and small amounts of brown pigment. Blue eyes form in a similar way, but without lipochrome. In this case, very little pigment is present at all, so light is scattered and only the shorter blue wavelengths are reflected back, just like the way the sky appears blue.

Green eyes require a very specific and rare combination of genetic variants across multiple genes. Around 75% of eye color is linked to the OCA2 gene, which helps control melanin production by influencing the development of melanosomes—cell structures that produce and store pigment. Another key gene, HERC2, can reduce OCA2 activity depending on its variant, resulting in less melanin and lighter eyes.

While only around 2% of people worldwide have green eyes, the figure is slightly higher in some regions. In the United States, for instance, around 9% of people have green eyes, while in parts of Northern and Central Europe—including Ireland and Scotland—estimates rise to roughly 10–20%.

Our diverse eyes are a reminder of just how finely tuned and unpredictable human genetics can be. And even if you’re not part of the 2% with green eyes, you’re still entirely unique.