Let's talk aboutHair Colour & Genetics

How it works

Our bodies produce a substance called pigment, and pigments are responsible for the colourof our skin, hair, and eyes. When scientists talk about the pigments people produce, they’re typically referring to melanin. There are two types of melanin you should remember: eumelanin, which is brown/black, and pheomelanin, which is red/yellow.The lightness or darkness of your hair depends on the amount of different types of melanin you produce. People with dark hair produce a lot of eumelanin, and people with light hair generally produce it too, just not as much. If you produce pheomelanin, your hair could be more or less red, depending on how much of the pigment you produce.Hair cells don’t make their own pigment. Instead, specialized skin cells within the hair follicle create pigment. These skin cells are called melanocytes.

The genetic link

You might wonder if there’s a single gene that causes hair to be blonde, brown, or black. It turns out hundreds of genes influence hair colour. Some of the genes associated with hair colour also influence eye colour, skin pigmentation, and freckles. These partly-overlapping genetics help explain why a person’s hair, skin and eyes are sometimes similar in terms of being lighter or darker.

Did you know?

Your hair may change colour at different points in your life naturally, without the help of a bottle of dye. Some hair types can get lighter when exposed to lots of sunshine, though the difference is more noticeable in lighter shades. That’s because UV rays cause melanin in the hair to break down. Changing hormone levels at puberty also affect melanin production, causing some children’s hair to turn from lighter to darker as they approach adulthood. In older age, hair often stops producing melanin and loses its colour.

Explore more

Sadly, there are no genetic variants for blue hair-at least not at this stage of human evolution. But that doesn’t mean there aren’t lots of interesting things to learn about your natural hair colour! 23andMe’s Health + Ancestry Service can help you find out if you’re likely to have light or dark hair based on your genetics.

References

23andMe Blog (2018, April 16). “Untangling the Genetics of Hair Colour.” Retrieved October 25, 2018, from https://blog.23andme.com/23andme-research/untangling-the-genetics-of-hair-colour/.

Arck PC et al. (2006). “Towards a “free radical theory of graying”: melanocyte apoptosis in the aging human hair follicle is an indicator of oxidative stress induced tissue damage.” FASEB J. 20(9):1567-9.

Ito S and Wakamatsu K. (2011). “Diversity of human hair pigmentation as studied by chemical analysis of eumelanin and pheomelanin.” J Eur Acad Dermatol Venereol. 25(12):1369-80.

Nogueira AC and Joekes I. (2004). “Hair colour changes and protein damage caused by ultraviolet radiation.” Photochem Photobiol B, Biol. 74(2-3):109-17.

Pers et al. (2015). “Biological interpretation of genome-wide association studies using predicted gene functions.” Nat Commun. 6:5890.

Slominski A et al. (2005). “Hair follicle pigmentation.” J Invest Dermatol. 124(1):13-21.

Sturm RA. (2009). “Molecular genetics of human pigmentation diversity.” Hum Mol Genet. 18(R1):R9-17.

Sulem P et al. (2007). “Genetic determinants of hair, eye and skin pigmentation in Europeans.” Nat Genet. 39(12):1443-52.

Wood JM et al. (2009). “Senile hair graying: H2O2-mediated oxidative stress affects human hair colour by blunting methionine sulfoxide repair.” FASEB J. 23(7):2065-75.