The Science Behind the Color of Your Eyes

Have you ever wondered why your eyes are the color they are? Most people assume their eye color is a mix of both parents, but it’s more complicated than this. There are actually several different things that can affect your eye color, which is part of their mystery. No wonder why people are fascinated by their baby’s eyes and if/when they will change! 

Whether you are curious about your eyes or your baby’s eyes, here is some information on what influences eye color. 


Contrary to what you may have learned in school, eye color is more complex than having dominant (e.g., brown) and recessive (e.g., blue) traits. Human eye color comes from three genes in total, and two of them are well-understood. These two genes account for the most common eye colors, including brown, blue and green. 

Additionally, there are multiple possibilities for what can come from the genes in terms of eye color. The baby could have brown eyes, blue eyes or green eyes. In other words, there is no “set” color but several possibilities based on the genetic information. 

Melanin Production 

Have you ever noticed that a baby’s eye color can change after birth? This happens because melanin is being produced. Most Caucasian babies are not born with melanin, a brown pigment. This is why their eyes are blue. However, melanin usually starts developing after birth, which is why babies’ eyes darken. It can take some children three years to get their full eye color

Dark Colors 

Typically, dark colors dominate, so brown will win over green, and green will win over blue. So, if both parents have brown eyes, it’s likely that their child will, too. However, if one parent has brown eyes and the other has blue eyes, it’s not a given that the baby will end up with brown eyes. This is where genetics get tricky. Plus, there are other combinations such as gray or hazel. 

Older Age 

To much surprise, it’s not just babies’ eyes that change color. Adults can, too. About 10-15 percent of Caucasian people (mostly those with light eyes) have eyes that change color in later life. Light brown eyes can get lighter and look hazel, whereas hazel eyes can get darker. These changes happen because of melanin production in the body and/or pigment changes in the iris. 


Certain emotions are also said to change the color of your eyes. When the pupil changes, the pigments in the iris contract or expand, causing the eye to change color. Usually, this is a slight difference, but it’s the reason why some people say their eyes change color when they’re mad or happy. There are even theories that eye color influences personality.

We do want to point out that if your eye color changes dramatically, or if only one eye changes color, it’s important to see a doctor. These changes can be a sign of a serious condition, such as pigmentary glaucoma. By setting up an eye appointment with an eye specialist in Brooklyn NY, you can get the answers you need to keep your eyes healthy.