Monday, February 20, 2012

Will Your Newborn Have Blue Eyes?

Have you ever wondered what eye color your child will have? Many parents, seeing their newborn’s blue eyes, hope they retain that deep blue hue forever. But they might be in for a surprise!

Eye color is determined by the brown pigment, melanin. Depending on the concentration of melanin in the iris, your child ends up with blue, green, or brown eyes. All newborns have blue eyes because at the time of birth, their irises have not started producing melanin. The real eye color settles in between 6-9 months of age and is mainly determined by genetics.

Research has identified many genes that are responsible for our permanent eye color, but there are two that are best understood. I'll call them gene A and gene B. Each of these genes has 2 variants: A-brown and A-blue, and B-green and B-blue. Our eye color depends on which combination we inherit from our parents. This model provides the best understanding of how eye color is inherited, but it does not provide an explanation for the occurrence of gray eyes, or shades of blue, green, or brown. So these eye colors still remain a mystery.

Brown is the most common eye color in the world. In many populations, brown is the only eye color present. Brown eyes contain the most amount of melanin, and they are common in Africa, Americas, and Asia. Brown eye color is rare in countries such as Germany, Poland, Finland, or Sweden.

Green eyes are among the rarest eye color, and they are common in Northern and Eastern Europe. A study published in Preventive Medicine reports that almost 90% of the Icelandic population has either green or blue eyes. Another study of Icelander and Dutch adults found that green eyes are much more prevalent in women than in men. 

A geneticist wrote a program, called the eye color calculator, founded on the principle of probability. This program allows you to predict your child’s eye color based on the closest approximation of the eye color of people in your family tree. You can check it out here: Eye Color Calculator. Since we don't yet know how eye color is exactly determined, use this eye color calculator only for fun.

Whether your child ends up with blue or brown eyes, remember to love them for who they are. Eye color does not determine personality or inner beauty!

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