Can we predict hair color in babies?

Hair color is one of the parts of genetics that can sometimes be tricky to pinpoint exactly. But with knowledge of inheritance, and gene functions, we can have fun trying!

The Basics of Hair Color Genetics

Our hair color is mainly determined by melanin, which is a complex molecule in our body that determines the intensity of colors. There are two types of melanin:

1. Eumelanin: Responsible for brown and black pigments
2. Pheomelanin: Produces red and yellow pigments

The more eumelanin, the darker the color, which is why we have different shades of brown and black hair. Similarly, the more pheomelanin, the more red tones will be in your hair. Over 100 genes assist in producing and distributing all four of these pigments! The main players involved are MC1R, ASIP, and TYR.¹

Inheritance Patterns in Hair Color

Because so many genes work together to create our hair color, it is considered a polygenic trait. When the genes from each parent come together to make a baby, the hair color genes interact with each other. Sometimes they’ll help build each other up, other times they can silence one another. 

For example, the MC1R gene mentioned earlier can have a non-working copy, which would lead to a red hair color. But, if one parent passes down a non-working copy, and the other passes down a working copy, the result would be a middle ground of red, maybe more like auburn or strawberry blonde! Interactions like these create a hair color based on the combination of all of the genes.

Factors Affecting Prediction

But even using this information might not tell us what our hair will look like through every step of our lives, for a lot of reasons! For one thing, the interactions we talked about before can be tricky to understand and to make a prediction based off of. 

For example, blonde hair is typically thought to be a recessive trait, meaning that in order to be blonde, a person can only have the blonde versions of the genes that determine hair color. This might lead one to think that if two people with blonde hair had a baby, that baby would have blonde hair too. However, it isn’t actually this simple, and while this often happens, it doesn’t have to! A gene called KITLG has been noted to impact the range of blonde to brunette, so a baby with a variant in this gene may have brown hair - even if their parents are both blonde.² Genetics isn’t always black and white, so neither is hair color!

Our environment also impacts the expression of our genes. For example, being in the sun can make our hair look lighter, even if our genes tell it to be dark.³ Similarly, nutrition, and other environmental exposures can impact our hair color, alongside our genes.

Our age adds to this unpredictability! Sometimes babies are born with light hair, just as predicted by their genes! But, as they age, their hair can get darker.⁴ This is because melanin production can increase as they grow into adulthood.

Aging impacts hair color in adults too. Eventually, hair follicles start producing less and less melanin. This results in our hair turning shades of grey. While this isn’t genetic, it’s interesting to think about the many other factors that impact our hair color.

Conclusion

Overall, we might not be able to exactly predict a child’s hair color based on their parents genes, but it can be really fun to try! Genes answer a lot of questions about what we look like, but they also add even more questions. So when trying to predict things like hair color, it’s a good idea to start with genetics, but you also have to think about what other factors are at play!