A child’s eyes can change color after birth. Many parents notice their newborn’s initial eye color gradually shifting over the first few months or years of life. This natural phenomenon is a fascinating aspect of human development, often leading to curiosity about the underlying biological processes. Understanding why and when these changes occur helps clarify this common experience.
The Science Behind Eye Color
Eye color originates from the iris, the colored part of the eye that surrounds the pupil. The primary pigment responsible for eye color is melanin. Specialized cells within the iris, called melanocytes, produce this melanin. The amount and distribution of melanin within the iris determine the visible eye color.
Eyes with high concentrations of melanin appear brown, as the pigment absorbs most light entering the eye. Intermediate melanin levels lead to colors like green, hazel, or amber, where a mix of melanin reflects light to create various tones. Conversely, eyes with very low melanin content in the iris appear blue because more light scatters within the stroma, a part of the iris. This light scattering is the same phenomenon that makes the sky appear blue.
Why a Child’s Eye Color Changes
A child’s eye color often changes due to the gradual development of melanin. Many babies are born with little melanin in their irises, resulting in lighter eye colors like blue or gray. The dark environment inside the womb limits initial pigment production.
After birth, as the baby is exposed to light, the melanocytes in the iris become more active and begin to produce additional melanin. This increased melanin production can cause the eyes to darken or change hue over time. For instance, eyes that were initially blue may transition to green, hazel, or brown as more pigment accumulates. This shift from lighter to darker shades is driven by the body’s ongoing melanin development.
When Eye Color Typically Settles
The timeline for a child’s eye color change varies. While eye color can begin to change within the first few months of life, the most notable shifts often occur between three and nine months of age. Many babies will have a permanent eye color by the time they reach nine months to one year old.
Some children may experience continued, more subtle changes in eye color until they are up to three years old, and occasionally even until around six years of age. The exact timing of when eye color stabilizes depends on the individual child’s melanin production.
Genetics and Permanent Eye Color
Genetics plays the primary role in determining a child’s permanent eye color. Genes inherited from both parents influence the amount and type of melanin produced in their irises. While it was once thought that eye color inheritance followed a simple dominant/recessive pattern, scientists now understand that multiple genes are involved.
Over 16 genes contribute to eye color, with two genes, OCA2 and HERC2, playing important roles. These genes regulate melanin production and distribution, influencing the final hue. The interplay of these genes and their variations can lead to a wide spectrum of eye colors, making it possible for children to have eye colors different from either parent. Once melanin production stabilizes, the eye color is permanent.