Will your new baby start with the classic blue eyes? And will they stay that way? Despite what you may have been taught, eye color inheritance is very complicated. We'll walk you through the odds that your child will inherit your eye colour, and your sight problems. We'll also cover some wild traits, like a pair of eyes with two different colors, albinism, and even purple eyes. Here's what you need to know!
15 Not as Simple as It Sounds
Perhaps you once heard that eye color is determined by one gene, and that brown eyes are dominant over blue eyes so that if a child has the genetics for both colors they'll always end up with brown eyes. Well, scientists have found that eye color is much more complicated than we originally thought. There are at least four, and there may be fifteen or more, genes that contribute to eye color and so we can't predict with certainty what a child will inherit. Yet, this new complexity in eye color genetics allows for some interesting possibilities: two blue-eyed parents can have a brown-eyed child just like two brown-eyed parents can have a blue-eyed child. Let's start with some specifics.
14 The Eye "Ring"
The iris is the colored part of the eye and is found all around the black pupil. The iris is the muscle that contracts to adjust the size of the pupil, changing how much light gets into the eye. Yet, there is another part of the eye that's important for color: the Limbal ring. It's a dark ring around the iris. Your child's will likely be very distinct, but they do tend to get smaller and lighter with age - while on some people they are imperceptible. As they get smaller and lighter, the color of your eyes appear to lighten with them.
13 Some Children Are Born with Blue Eyes
Children with light skin will likely be born with blue eyes. This is because the same substance that produces skin colour, melanin, also produces eye colour. Children with less melanin will have blue eyes that can change colour until about three years old. These parents will have to play a waiting game to know for sure what colour their child's eyes will be, but, of course, they may remain blue.
12 Heterochromia: Two Different Colored Eyes
Some babies are born with, or develop, two different eye colors. If you notice this, be sure to mention it to your doctor as it may be a sign of Horner's Syndrome, which can be serious. There are other causes of heterochromia including: trauma in the womb, inflammation, chimerism, another (harmless) genetic disorder, or a freckle on one iris. The freckle is usually harmless, especially in young people, and may make for all kinds of odd or beautiful eyes.
11 Blue Eyes
If you love blue eyes you'll be disappointed to know that predicting them is now very complicated, with the ten or so genes involved. But, we know how the two major genes in eye colour genetics work, and if you and your partner both have blue eyes you're likely to pass it on. If one of you has brown eyes your chances are much slimmer, probably around twenty-five per cent. They do improve somewhat, to about fifty per cent, if the brown-eyes parent carries a recessive gene for blue eyes. You're more likely to carry this recessive blue eyed gene if your siblings and/or your parents have blue eyes, but its no guarantee. Also, it's still possible to have a brown eyed child, even if both you and your partner have light eyes.
10 Grey Eyes
Grey eyes aren't an urban myth, but they are a mystery. There are a few theories as to what makes eyes grey. Some think that grey eyes have even less melanin than blue eyes, while others think that the shape of the eye is different, so the light is refracted at a different angle, which changes the colour. But, because no one knows what causes this eye colour no one can predict if your child will have grey eyes or not.
9 Green Eyes
So far we've talked about melanin as though it's only one thing, but there are actually two types of melanin in humans: eumelanin and pheomelanin. Eumelanin is dark and responsible for dark skin and dark eye colour. Pheomelanin is yellow, and is responsible for green eye colour. Why green? When yellow light refracts through the shape of the human eye it turns green. Its the same reason that the sky is blue, as the light changes angles when it moves through the atmosphere and becomes blue. Green eyes aren't very likely, but they are common to both Irish and German ancestries.
8 Brown Eyes
There's no big mystery here, either. Brown eyes are the result of high levels of eumelanin. regardless of the level of pheomelanin, as eumelanin usually cancels it out as far as colour is concerned. If you have brown eyes you're likely to pass them on, although its not impossible for your child to have other eye colors. If you feel like brown eyes are a little overlooked, don't worry, people actually find them more youthful than other eye colors and so they receive their fair share of adoration.
7 Hazel Eyes
These eyes are a simple mixture between blue and green eyes, or between eumelanin and pheomelanin. The mixture explains why the eye sometimes appears more green, and sometimes appears more brown, as lighting conditions or surrounding colors emphasize one melanin or the other.
6 Amber Eyes
Keeping in mind that human eye colour occurs on a spectrum, amber eyes are a variant of brown eyes. These eyes appear in stunning shades of warm browns to almost honey yellow. However, little is certain about how this eye colour is formed, never mind how it is passed on.
5 Purple Eyes
Although there's a popular myth that purple, or violet eyes exist, they don't. The myth also argues that people with purple eyes also have super human gifts, so its no surprise that the myth originated in fan fiction.
4 Red Eyes: Albinism
This is a very rare condition that results in very light, even seemingly pure white, hair and skin colour. Sometimes the eyes of people with albinism can appear red, because in some lighting the blood vessels at the back of eye can be seen due to the total lack of melanin. Otherwise the eyes appear blue, or even darker colors depending on the type of albinism. Though children with albinism are usually born to parents without it, and though albinism can occur in any ethnicity, only one in 17,000 Americans have albinism. Your child is very unlikely to be born with albinism.
3 Will Your Child Need Glasses?
There are other eye genetics that you could pass onto your child, including the need for glasses. Both nearsightedness and farsightedness are very likely to be determined by genetics, but the inheritance isn't cut and dry. Research from 2013 suggests that there is a strong environmental component to nearsightedness, including a lack of natural light during a child's eye development, making its occurrence hard to predict. It's best to get your child's eyes checked as they begin school, and frequently as they grow.
2 Color Blindness
Those who are color blind were usually born with it and are more often boys than girls. The genes for red/green and blue colour blindness are carried on the X chromosome, so when a girl inherits this gene they usually have a healthy second X chromosome that prevents the color blindness. Men, however, have a Y chromosome instead and will be color blind if they have one copy of color blindness genes. Your son will have a chance of being color blind if their maternal grandfather was. For sons, the father's genes don't matter as the father only passes on a Y chromosome. On the other hand, your daughter may become a carrier if her father is color blind, because he does pass down an X chromosome to her.
1 Other Hereditary Blindness
Blindness is very unlikely. For example, only five out of a thousand children will be born with cataracts, which cause blindness without treatment . Despite the low odds, it is important to bring any concerns you have about your child's sight to your doctor. Surgery for congenital eye cataracts should and can be done before the child is four months old, which will prevent the child from becoming blind. The sooner any potential sight issue is caught, the less of an affect it may have on your child's development.