There are well defined laws of nature which dictate what color your baby's eyes will be, but a lot of this is also left up to chance. Predicting infant eye color rests on probability, but that doesn't mean we can't have fun and find out what our unborn baby's eye color is most likely to be.

Brown is the most common color for human eyes because the gene that codes for them is dominant. The gene that codes for green eyes is recessive, meaning that if one parent has brown eyes and the other has green, it's far more likely that the child will have brown eyes. Interestingly, in this case, it is also possible for the child to have blue eyes (12.5%); albeit one of the least probable outcomes. Perhaps the most unusual outcome is for a child to have heterochromia; a condition characterized by one eye being of a different color than the other.

You may assume that if a child's parents both have the same eye color then the child is guaranteed to also have that color. This is not necessarily true. A child with parents who both have blue eyes is 99% likely to also have blue eyes. However, there is a 1% chance they will inherit green eyes instead. Similarly, both parents having brown eyes can give rise to an 18.75% chance of the child having green eyes and 6.25% of them having blue eyes. Green eyes are only expressed by 2% of the population, and when two parents with green eyes have a child that infant has an incredible 75% chance of expressing that gene too. They are 25% likely to express blue eyes and less than 1% likely to have brown eyes.

Explaining how to predict exact infant eye color for every combination of parental eye colors in one article is impossible. However, there are many simple charts available online which give a clear and concise guide to the probabilities. You should also remember that some anomalies are found in infant eye color due to the eye colors of maternal and paternal grandparents as well. For instance, blue eyes are far more likely to occur in a child that inherits red hair. The child's parents themselves may not have red hair, but this gene often skips a generation and is expressed in a grandchild instead, giving rise to blue eyes and red hair even if both parents have black hair and brown eyes.

Many parents assume that their baby's eyes will be blue for the rest of their lives. This is, however, not always true as a newborn baby's eyes are often blue before they take on their actual pigment. It's not unusual for an infant to be born with bright blue eyes which then turn deep brown just weeks or even days later.

So you see, the process of predicting infant eye color is a complex and confusing one which is never 100% certain. Perhaps in a society where it's possible to know our baby's gender, weight and health before they are born, not knowing the exact color of their eyes is the only surprise we get and it's one that we should hang on to!

Stan Tian

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