How does someone get two different-colored eyes?


Heterochromia is typically genetic and is fairly rare in humans. It is more common in dogs and cats!

Ever been curious about what causes people to have two different colored eyes? You are not alone. Having two different colored eyes is a condition called heterochromia. Eye color is determined by two factors: pigment, called melanin, and the amount or pattern of that pigment. All of this is ultimately controlled by your genes. So, in the case of heterochromia, what genes dictate two different eye colors?

What Causes Heterochromia?

Well, we already know that your DNA does but why? There are actually two reasons someone might have heterochromia. First, they are born that way. Scientists have hypothesized many different reasons for this, and so far we know it comes down to a lack of genetic diversity. Most cases of this condition are hereditary although it still remains fairly rare overall (occurs in 6 out of 1,000 or 0.6% of people).

Even though genetics is the more common reason for heterochromia, it can be acquired through other conditions or diseases. In this case, a person’s eyes would change color which could be a symptom of an underlying issue. That is why it is always important to have check-ups with your doctor and regular eye exams.

Eye Superstitions!

While it wasn’t actually named until 1947 by a Dutch ophthalmologist, Petrus Johannes Waardenburg, it has been around since the beginning of people. So, it comes as no surprise that there are folklores about people with two different colored eyes. To us, an intriguing feature, but to others, maybe not so much.

In some Native American cultures, dogs with two different eye colors were thought to have the ability to look into heaven and earth. They called this having “ghost eyes”. In other Eastern European cultures, heterochromia was a sign that a newborn’s eyes have been switched out with a witch’s!

Whatever you believe, one thing is for sure, heterochromia is mostly benign. However, if you notice a change in color of your eyes, you should come in for an appointment or reach out to your healthcare professional. Our eyes are essential to our health and our bodies. And, taking proper care of them both through routine doctor visits is crucial. For more information on topics about your eye health, check out our blog.