It is a question that scientists have long overlooked: how is the color of our eyes determined? Dutch and British researchers offer new answers, but at the same time they make things a lot more complicated. They found as many as 50 additional genes that play a role in this, bringing the total of genes involved to 61. These new insights can be useful, among other things, for the treatment of eye diseases and for solving crimes.

What makes someone have blue, brown, gray or green eyes? The answer lies in our DNA, but the search for the exact cause has not been easy. For a long time, researchers thought there were only one or two genes at fault, until relatively recent studies provided evidence that at least 11 genes were involved. Now it turns out that there are even at least 61, according to scientists from the Dutch Erasmus Medical Center and the British university King’s College London.

For their study, the researchers analyzed the DNA of nearly 195,000 people in Europe and Asia. They knew the eye color of those people and used high-tech techniques in their DNA to look for things that have something to do with those color eyes. This allowed them to identify 50 new genes associated with eye color.

Not just hereditary

The discovery provides additional evidence that the eye color is not simply determined hereditarily. We often wonder how two parents with blue eyes have a child with brown eyes, as if something would not be right. But now it turns out that this kind of mistrust is misplaced, because there are a lot of genes that influence the eye color.

Treatment of eye diseases

According to the researchers, these findings may help to improve the treatment of eye diseases. Because there are several conditions in which the eye color plays an important role, such as pigmentary glaucoma and ocular albinism.

Solving crimes

The new insights could also help solve crimes. By analyzing DNA traces, forensic investigators can already find out with great certainty whether an offender has blue or brown eyes. This analysis is likely to become even more accurate with the additional genes. For example, scientists hope that they will now also be able to find intermediate eye colors, different from brown and blue.