A newborn’s eye color is based on genetics. Genes trigger the production and distribution of pigments. A precise combination and concentration of pigments make up a person’s eye color.
This article discusses baby eye color, including how and when a newborn’s eyes change color. It also explains the probability of having a brown- or blue-eyed baby based on the parents’ and grandparents’ eye color and how to predict eye color.
What Determines a Baby’s Eye Color?
Baby eye color is determined by a substance called melanin. Melanin is a dark pigment contained in the iris, the structure that controls how much light is allowed into the eye. The color of the iris is determined by the amount of melanin in the iris. Light eyes have very little pigment, whereas darker eyes have a lot.
In newborns, the pigmentation process of the iris isn’t yet complete. Babies with darker skin are usually born with dark eyes that stay relatively dark. Iris color in lighter-skinned babies is usually a blue or bluish-gray color at birth, then changes as they grow.
When Is Eye Color Set?
Permanent eye color is not set until a baby is at least 9 months old, so wait until your child’s first birthday to determine what color they will be. Even then, sometimes you may find little surprises. Subtle color changes can still occur all the way up until about 6 years of age. For example, green eyes may slowly turn hazel or hazel may slowly grow to a darker brown.
An infant’s eye color is influenced by the eye color of their parents. Eye color is often studied in the field of genetics because of its inheritance patterns but is still not fully understood. Eye color inheritance patterns are much more complicated than what we learn in basic genetics taught in high school biology.
Your baby’s final eye color depends a lot on you and your co-parent. We used to think that brown was dominant and blue was recessive. But modern science has shown that eye color is not at all that simple.
Eye color is controlled by three basic genes. Researchers understand two of those genes really well, and one of them is still a bit of a mystery. These genes control the development of green, brown, and blue eye color. Gray, hazel, and other combinations are more difficult to predict.
Baby Eye Color Predictor
It’s hard to predict the exact color a baby’s eyes will have. However, there are some strong probabilities depending on the parents’ eye colors. Some examples:
If both parents’ eyes are brown, but one of them has a blue-eyed parent, then you have more of a chance that your baby’s eyes may stay blue. If both parents have blue eyes, then there is a pretty good chance that your baby’s eyes will stay blue. If one parent has blue eyes and the other brown, then your baby’s eyes have a 50% chance of either shade. If one parent has blue eyes and the other has brown eyes, the children could end up with green or hazel-colored eyes.
You might assume that neither eye color seems to be the dominant gene, so they are a perfect mix. However, science shows that eye colors don’t come out as an exact blend, but rather as pairs of genes that can create multiple possibilities.
Each person has two versions (alleles) of a gene, one from each parent. Eye color genes are either dominant (brown) or recessive (blue). If the two alleles are different, the dominant gene will be expressed. Recessive genes are only expressed when both alleles match.
