Where Do Green Eyes Come From | Genetics Explained.
Green eyes are some of the most beautiful and rarest eyes you can have, but did you know that they come from genetics; Green eyes are caused by the gene OCA2, which creates melanin.
This melanin is the pigment that turns your eye color into its green hue, and it can also be found in humans with green eyes and other animals. However, despite having this gene in common with most people who have green eyes, it’s not passed down directly to children when their parents with green eyes have kids together, so how do we get them;
Blue Eyes; When Things Go Wrong
If you have blue eyes, your children are likely to be born with blue eyes. It’s all about recessive genes at work!
One of your parents had to carry a gene for brown eyes and one for blue for you to have inherited two copies of a gene that codes for blue. If both parents had brown eyes, there is only a 25% chance they’ll pass on a brown-eye recessive gene meaning three out of four times; their kids will inherit at least one copy of their DNA’s blue gene instead.
When both parents have blue eyes, there is a 75% chance they’ll pass on a blue-eyed gene to their offspring (so long as neither parent carries any brown eye genes). As it turns out, if one of your parents has brown eyes and one has blue, there’s still only a 50/50 shot that you’ll end up with two copies of your mother or father’s eye color gene.
Brown Eyes; Common Traits
Brown eye color is one of four primary eye colors, but it varies in shades and tones as much as blue, green, and brown eye colors.
Brown eyes are considered a dominant trait that typically comes from parents who carry brown recessive genes that combine to create brown-eyed children (like parents with brown eyes can have a blue-eyed child).
If both parents have brown eyes, there’s a 50/50 chance of their child having brown or blue/green/hazel/etc., making eye color a handy marker when determining ancestry.
When one parent has dark hair and another light or blond hair, it’s easy to see how their child could inherit utterly different hair color yet wholly different eye color.
Green Eyes: Where Do They Come From?
Green eyes appear when both parents have a recessive gene for them (meaning they need to inherit it from both parents). If one parent has brown eyes and another has blue, there is a 25% chance their offspring will have green eyes.
It gets more complicated if one or both of your parents have blue or brown eyes and genes for green or hazel. All these factors affect how likely you are to develop specific eye colors, so it’s hard to predict what your child might look like without genetic testing which isn’t an option unless you can afford tens of thousands of dollars (not really).
Instead, let’s focus on how and why some people get specific eye colors in the first place. Here’s what happens: Melanin is responsible for darkening our skin, hair, and eyes.
People with brown eyes have large amounts of melanin in their irises; those with blue eyes don’t produce much melanin, while those with green or hazel eyes fall somewhere in between.
That’s because each color comes from a specific type of melanin: eumelanin produces brown/black/dark-colored hair and skin; pheomelanin produces red/yellow/orange-colored hair and skin; while neuromelanin (found only in nerve cells) gives us gray/white hair.
How Much Is in The Genes
In most cases, genes account for about 30% of a person’s eye color; both of your parents can have brown eyes, and you might still end up with blue or green peppers.
But suppose one parent has blue or green eyes. In that case, there’s a much higher chance that you will inherit those same eye colors instead of brown (for example, only 20% of children with two blue-eyed parents will inherit brown eyes).
This is because many genes influence eye color in subtle ways, so-called modifier genes. Some scientists believe that as many as 10 or 15 are at play when determining what shade our peepers will be growing up.
What Causes Color Variation in Eyes?
Three known genes control eye color: EYCL1, EYCL3, and PAX6. Variations in these genes have been linked to green eyes but, more commonly, brown or blue-grey hues.
That’s because even if you have a green gene, there needs to be another gene present to give your iris color; otherwise, it appears as a brown or grey shade instead.
The protein melanin is produced by cells called melanocytes in your body’s skin and retina (the light-sensitive tissue at the back of your eye). This pigment determines whether your iris will be blue, brown, or something else entirely and is responsible for skin tone and hair color too!
The Role of Genes in Eye Color
The color of your eyes is determined by melanin. This pigment determines whether your iris is brown, blue, or green.
The amount of melanin in your iris determines how light or dark your eye color appears. Dark-eyed people have more melanin in their irises than light-eyed people; conversely, those with less melanin have more delicate eyes than those with more.
However, although eye color is often thought to be a simple matter of how much melanin someone has, and that’s it, there are several other genes involved as well, which influence eye color to varying degrees depending on both parents’ DNA make-up.
In summary, when we compare and contrast, there is a significant difference between blue and green eyes because of the pigmentation of specific proteins, one being OCA2. Another is HERC2, which contributes to gene interactions resulting in either blue or brown-green colored irises.
And just as there are so many differences between eye colors, ethnicity plays a huge role in determining what color an individual’s eyes will be due to family heredity. For example, individuals with Middle Eastern heritage are more likely to have brown/black colored irises. In contrast, people of Northern European descent have lighter eye colors such as blues, greens, and yellows.