Authors: Bamba; Golden Jackson, PhD; Cristina Hernandez; Delroy Daley; and David Rodda, PhD, Associate Professor of Molecular Cell Biology of the AUC School of Medicine.
Hey friends! It’s Bamba here and I can’t wait to talk to you about some exciting, cool science today! This self-quarantine gave me a lot of time to think and I wondered, “How do humans get the colour of their eyes?”
Genetic expert, Dr. Rodda of AUC School of Medicine helped me explore this eye-opening mystery… get it? “Eye-opening?” Ha-ha! Well, the answer to that question is in your genes – not the ones you wear!
Did you know that humans are born with pre-made instructions? Yes, that’s right! Humans and all other organisms have DNA that holds instructions, like a user’s manual, for how our bodies grow and develop!
DNA is a tiny, little molecule found inside every cell of our bodies and the instructions in the DNA are called genes. Genes determine how tall you will be, the texture of your hair, the colour of your eyes, and much more.
You have two copies of all your genes, one copy you received from your mother, the other copy you received from your father. Next, your genes in DNA are wrapped up in chromosomes – the bundle that packages your genes together.
So, how do your genes determine your eye colour? According to experts, there are eight genes that control the colour of your eyes. You have two sets of these genes that came from each of your parents. Sometimes you might receive different versions of these genes from your parents.
For example, you may receive a gene that makes blue eyes from your father, and a gene that makes brown eyes from your mother. So, what colour would your eyes be then? That depends on what scientists call the dominance of the genes.
With eye colour, brown eyes are dominant, so if you have genes for both brown and blue eyes, your eyes will be brown. You can only have blue eyes if you don't have a gene for brown eyes. What about people who have green or hazel eyes? A different gene makes those colours, but still brown eyes are dominant, so just like with blue eyes, a person can only have green or hazel eyes if they don’t have a gene for brown eyes.
Did you know you can have different coloured eyes than your parents? If a child is born to parents who both have brown eyes, there is a greater chance of their child having brown eyes, but there is also a chance their child can have blue or green eyes. The chart shows the likelihood (chance) of a child having eyes of a particular colour based on the colour of their parents’ eyes.
Did you know the amount of melanin you have in your eyes is another factor that helps determine eye colour? Melanin is a pigment that people have that normally determines how dark or light their features are. For example, a darker skinned person has more melanin in their skin than a lighter skinned person.
This is also true in eye colour. If your melanin gene is “turned on” high, then your eyes will be darker and browner. The less melanin in your eyes, then the lighter your eyes will be, resulting in green or blue eyes. No matter the size, shape, or shade of your skin, the colour of your eyes is based on genetics and chance!
Well there you have it! Another fun science exploration with you guys! Until next time, stay safe!