Eye color is one of many inherited characteristics that tie us to our parents. It’s something that fascinates parents and families of new babies as they try to guess what color the child’s eyes will be. Determining eye color is a complicated equation that can’t be answered until the child is born. And even then, in some instances, eye color can change based on age, and even emotion.
The ring of color in the human eye is known as the iris. The iris contains pigmentation that makes the eye appear to be one of several common colors, including brown, blue, green, hazel, and gray, or a combination of these colors. Most babies are born with blue eyes. This is because melanin, which is a brown pigment, is usually not present in the eye at birth. As the baby grows and melanin is produced, the iris gradually darkens to its final color, which may or may not match the color of the parents.
The Genetics of Eye Colors
It was once believed that brown eyes were dominant, blue eyes were “recessive” or least dominant, and green eyes were somewhere in the middle. Scientists now know that eye color is much more complicated than that. Three genes have been identified as contributing to eye color, and it’s likely that more genes will be found to participate as further study is done.
On a basic level, genes are bits of information that are inherited from the parents. Inside every cell in the human body, there are structures called chromosomes that carry genes which provide genetic information. You may have seen chromosomes illustrated as a spiral step-ladder. When a baby is conceived, half of the information for each chromosome is provided by the father and half is provided by the mother. So each chromosome has two matching parts that pair up to provide the complete information that determines all the characteristics of the new baby, including eye color.
Predicting Eye Colors
If eyes came in only two colors, blue or brown, it would be simple to determine the odds that a baby would have either color. Because there are multiple genes involved in determining eye color, there is no simple formula that can be used.