Many new parents notice their newborn’s striking blue eyes and wonder if the color will remain. Eye color in infants is a dynamic trait, frequently changing as a baby grows. This often sparks curiosity about why many babies begin life with light eyes, even if their family members have darker shades.
The Prevalence of Blue Eyes at Birth
While “baby blues” is a common phrase, not all newborns have blue eyes. Research indicates the percentage of newborns with blue eyes varies and is not the majority. For example, a 2016 study of 192 newborns found about 20.8% had blue eyes at birth, while 63% had brown eyes. This prevalence differs across ethnic groups; Caucasian infants often have blue or gray eyes at birth, whereas babies of Asian, Black, or Hispanic descent typically have darker eyes.
The initial blue or grayish appearance in many newborns is due to limited melanin in the iris. Melanin is the pigment determining eye, hair, and skin color. At birth, melanocytes, the specialized cells producing melanin, have not fully activated or been exposed to light. Without much melanin to absorb light, light entering the iris scatters, creating a blue perception, similar to how the sky appears blue.
How Eye Color Develops and Changes
A baby’s eye color often changes during their first few months and years. As infants are exposed to light, their melanocytes begin producing and depositing melanin in the iris. The amount and type of melanin developed determines the child’s permanent eye color. Very little melanin results in blue eyes, more melanin leads to green or hazel, and a substantial amount results in brown eyes.
Significant eye color changes usually occur between three and nine months, with many babies’ true eye color apparent around their first birthday. Some children may experience subtle shifts up to three years old, and occasionally, changes continue into adulthood for those with lighter eye colors. Eye color generally progresses from lighter to darker shades as melanin production increases, meaning dark eyes are less likely to lighten.
Understanding Eye Color Determination
A person’s final eye color is primarily influenced by genetics, involving a complex interplay of multiple genes. While many genes contribute, OCA2 and HERC2, located on chromosome 15, are major players. The OCA2 gene provides instructions for producing the “P protein,” involved in melanin production and storage within the iris.
The HERC2 gene regulates OCA2, controlling its activity and influencing melanin production. Variations within these genes affect the quantity and quality of melanin, leading to the wide spectrum of human eye colors. This complex genetic inheritance explains why predicting a child’s eye color can be challenging and why, in rare instances, two blue-eyed parents might have a child with brown eyes.