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When do babies develop their permanent eye color?
Q:I have boy/girl twins, 3-months-old, with blue eyes. At what age will they develop their permanent eye color? Their father and I have brown eyes and we are half African-American, half Caucasian.
— Submitted by Jennifer in Dallas
Karen Sokal-Gutierrez, M.D., M.P.H.
Pediatrics
A:Jennifer, your babies’ eye color is determined by the genes they inherited from you and their father. Researchers have already identified three gene pairs that affect eye color, and there may be more. The genetics of children’s eye color is very complicated, but we’ll try to simplify it a bit.
Genes come in pairs: you inherit one from each of your parents. The gene for brown eyes tends to be dominant over blue eyes. So your and your partner’s brown eyes could have resulted from receiving either brown eye genes from both parents or brown from one and blue from the other. When, in turn, you and your partner each passed one of your genes to your children, it’s most likely that they got brown eyes, if one or both of you handed down a brown gene. But it’s also possible that they got blue eyes, if both of you handed down a blue gene. They might even get gray, green, or hazel eyes from combinations with the other gene pairs that affect eye color. In other words, blue, gray, green, or hazel eyes could come through to your children from their grandparents.
The genes for eye color determine the amount of melanin, a dark brown pigment, produced in the iris of the eyes. A lot of melanin leads to brown eyes; an intermediate amount leads to gray, green or hazel eyes; and a small amount leads to blue eyes. African-American, Latino, and Asian babies typically have more melanin and brown eyes at birth, and their eyes remain brown for life. Caucasian or part-Caucasian babies may have little melanin production at birth and dark blue or steel gray eyes. Over time, as the babies’ genes determine how much melanin gets produced in the babies’ eyes, their eyes may remain blue or may turn brown, gray, green, or hazel.
It was thought that babies’ eyes generally reached their final color by 6-12 months of age. But a long-term study of eye color found that 10-15% of peoples’ eye colors continued to change into adulthood. So be prepared for any surprise with your children’s eye color. And remember, since they’re not identical twins, they may have different eye color from each other as well.
Genes come in pairs: you inherit one from each of your parents. The gene for brown eyes tends to be dominant over blue eyes. So your and your partner’s brown eyes could have resulted from receiving either brown eye genes from both parents or brown from one and blue from the other. When, in turn, you and your partner each passed one of your genes to your children, it’s most likely that they got brown eyes, if one or both of you handed down a brown gene. But it’s also possible that they got blue eyes, if both of you handed down a blue gene. They might even get gray, green, or hazel eyes from combinations with the other gene pairs that affect eye color. In other words, blue, gray, green, or hazel eyes could come through to your children from their grandparents.
The genes for eye color determine the amount of melanin, a dark brown pigment, produced in the iris of the eyes. A lot of melanin leads to brown eyes; an intermediate amount leads to gray, green or hazel eyes; and a small amount leads to blue eyes. African-American, Latino, and Asian babies typically have more melanin and brown eyes at birth, and their eyes remain brown for life. Caucasian or part-Caucasian babies may have little melanin production at birth and dark blue or steel gray eyes. Over time, as the babies’ genes determine how much melanin gets produced in the babies’ eyes, their eyes may remain blue or may turn brown, gray, green, or hazel.
It was thought that babies’ eyes generally reached their final color by 6-12 months of age. But a long-term study of eye color found that 10-15% of peoples’ eye colors continued to change into adulthood. So be prepared for any surprise with your children’s eye color. And remember, since they’re not identical twins, they may have different eye color from each other as well.
