⚠️This fact has been debunked
The claimed ratio of 1 in 500 (0.2%) significantly overstates the prevalence of complete heterochromia. Recent peer-reviewed research from a 2022 study published in the Journal of Optometry found the actual prevalence to be 0.06% (approximately 1 in 1,587 people), which aligns with earlier studies from the 1960s. The condition is approximately three times rarer than this fact claims.
One in 500 humans has one blue eye and one brown eye.
The Truth About Having Two Different Colored Eyes
You've probably heard the claim that one in 500 people walks around with mismatched eyes—maybe one blue, one brown. It's the kind of statistic that gets repeated in trivia games and social media posts. There's just one problem: it's not true.
The actual prevalence of complete heterochromia—the medical term for having two completely different colored eyes—is about 1 in 1,600 people, or roughly 0.06% of the population. That makes the condition approximately three times rarer than the popular myth suggests.
Where the Numbers Come From
A 2022 study published in the Journal of Optometry analyzed over 11,000 high-resolution portraits of U.S. Military Academy cadets and found exactly seven cases of complete heterochromia. Their calculated prevalence of 0.063% closely matched research from the 1960s, suggesting this rarity has remained consistent across generations.
To put that in perspective: if you're in a crowded football stadium with 50,000 people, statistically only about 31 of them would have complete heterochromia. Not exactly common.
Why the Confusion?
The inflated "1 in 500" figure likely stems from confusion between different types of heterochromia:
- Complete heterochromia: Two entirely different colored eyes (the rare one)
- Sectoral heterochromia: One iris has a different colored segment or wedge
- Central heterochromia: The inner ring around the pupil is a different color than the outer iris
When you lump all types together, the numbers do increase—some sources suggest up to 0.6% of people have some form of heterochromia. But two completely different colored eyes? That's the genuinely rare version.
The Celebrity Effect
Part of why heterochromia seems more common than it is comes down to visibility. Celebrities and models with the condition—like Kate Bosworth, Mila Kunis, and Henry Cavill—get disproportionate attention precisely because it's unusual and striking. When millions of people see the same handful of famous faces with heterochromia, it creates an availability bias that makes the condition seem more prevalent than reality.
So the next time someone drops the "1 in 500" statistic at trivia night, you can set the record straight: complete heterochromia is real, it's fascinating, but it's about three times rarer than that viral factoid claims.