Just like skin color, a baby’s eyes change color due to exposure to sunlight. You’ll notice significant changes before their first birthday. The most noticeable ones will occur around 3 to 6 months after birth.
At this point, you can most likely predict the baby’s final eye color. However, wait a few more months for a more stable eye color.
According to eye experts, most babies will have their lifetime eye color by the time they’re 9 months old.4 However, some may take up to 3 years to have a permanent eye color.
What Color Are Babies’ Eyes When They’re Born?
Most babies (63%) are born with brown eyes, but color variations exist. Studies show newborns of Black, Indigenous, and People of Color (BIPOC) are likely to have brown eyes at birth.1
However, the brown shade may darken slightly with time. On the other hand, most Caucasian babies are born with blue or gray eyes that may change to depending on the amount of melanin present in the iris (the colored part of the eye).
What Determines Eye Color?
Melanin is a substance produced by cells known as melanocytes and it’s responsible for skin, hair, and eye color.2 Every baby has the same type of melanin in their eyes.
The amount and quality of this pigment determine the variations in eye color. Scientists have also defined eye color as an inherited trait.
The type of melanin responsible for brown eye color is eumelanin (black or brown). Pheomelanin (reddish-yellow) combines with the light-scattering effect of the iris (which makes eyes look blue) to make eyes appear green. Green eyes are the least common, accounting for only 9% of the US population.
Melanin Production
Eye color is determined by the amount and quality of melanin pigment in the front layer of the iris (stroma).5 Babies are often born with less melanin in the eyes due to the darker conditions in the womb.
After birth, exposure to sunlight activates the melanocytes to produce more melanin. Melanin production over time will vary from child to child, affecting the final eye color. Like fingerprints, every child’s amount of melanin produced is unique.
When light hits the irises of eyes with less melanin, it splits into various colors (Rayleigh scattering), causing hazel, gray, amber, green, red, or blue eyes. On the other hand, large amounts of melanin will result in a darker shade (dark brown).
Genetics
A baby’s family history will determine the amount of melanin they produce. Two brown-eyed parents will most likely have a brown-eyed baby. However, this is not guaranteed since one or both parents may have a recessive gene for blue eyes.
On the other hand, blue-eyed parents will most likely give birth to a blue-eyed baby. If only one parent has the blue eye gene, a blue or brown-eyed baby is likely.
Ethnicity/Region
Children born to Black, Asian, and Hispanic parents have dominantly brown-eye genes.7 In Europe, the colors may vary by region.
For example, eye color tends to be lighter in Northern Europe and darker in the South. Experts attribute this to climate variations, which affects the exposure level to sunlight.8
Health Conditions
Below are common conditions that affect the production of melanin in the eyes.
- Ocular albinism: It affects the pigmentation of the iris, resulting in very light eyes and vision issues
- Oculocutaneous albinism: It affects melanin production, producing fair or light-colored eyes, hair, and skin
- Heterochromia: It’s characterized by differently colored eyes and is caused by genetic changes, problems with eye development, injury, or disease
Other Factors that Contribute to Eye Color
A special gene called OCA2 or P gene activates melanocytes to produce melanin.6 The amount and quality of melanin produced is determined by a protein known as P protein. Less P protein means less melanin in the iris, hence lighter-colored eyes.
Another special gene that contributes to eye color is HERC2. It regulates the action of OCA2 by turning melanin production off or on. Other minor genes that contribute to eye color include:
- ASIP (Agouti Signaling Protein)
- IRF4 (Interferon Regulatory Factor 4)
- SLC24A4 gene
- SLC24A5 gene
- SLC45A2
- TPCN2 (Two Pore Segment Channel 2)
- TYR gene
- TYRP1 gene
Summary
Just like skin color, eye color in babies changes after 3 to 6 months of exposure to light. Babies with blue eyes may have amber, red, brown, green, or hazel eyes.
According to studies, children of Black, Indigenous, and People of Color (BIPOC) will likely have brown eyes at birth. Meanwhile, Caucasian babies are likely to have dark blue or gray eyes.
Various factors determine a baby’s eye color. These include melanin production, family history, ethnicity, genetics, and the presence of certain eye conditions.
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