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Is hair color determined by genetics?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Traits

Is hair color determined by genetics?

Hair color is determined by the type and amount of melanin pigment in the hair, a process regulated by multiple genes.

The Role of Melanin

Hair color is determined by the amount of a pigment called melanin in hair. An abundance of one type of melanin, called eumelanin, gives people black or brown hair. An abundance of another pigment, called pheomelanin, gives people red hair.

Melanin and Hair Color

  • Black: Large amount of eumelanin
  • Brown: Moderate amount of eumelanin
  • Blond: Very little eumelanin
  • Red: Mostly pheomelanin with a little eumelanin

Genetic Regulation

The type and amount of melanin in hair is determined by many genes. The best-studied hair-color gene in humans is MC1R. This gene provides instructions for making a protein called the melanocortin 1 receptor, which is involved in the pathway that produces melanin.

The melanocortin 1 receptor controls which type of melanin is produced by melanocytes:

  • Activated receptor: Stimulates cells to make eumelanin.
  • Deactivated/Blocked receptor: Cells make pheomelanin instead of eumelanin.

Most people have two functioning copies of the MC1R gene and have black or brown hair. Variations in the MC1R gene that cause it to be turned off (loss-of-function) lead to lower eumelanin production and higher pheomelanin production, resulting in strawberry blond, auburn, or red hair.

Other Genetic Factors

Many genes other than MC1R play a role in determining shades of hair color by controlling levels of eumelanin and pheomelanin. These include ASIP, DTNBP1, GPR143, HPS3, KITLG, MLPH, MYO5A, MYO7A, OCA2, SLC45A2, SLC24A5, TYRP1, TYR, ERCC6, GNAS, HERC2, IRF4, OBSCN, SLC24A4, TPCN2, and MITF. Some of these genes are associated with gene transcription, DNA repair, the transport of substances across cell membranes, or the structure of hair follicles.

Changes Over Time

Hair color may change over time. In people of European descent, light hair often darkens as individuals grow older, possibly due to the activation of certain hair-pigment proteins near puberty. Additionally, hair turns gray as the hair follicle loses its ability to make melanin, a process that is partly hereditary and influenced by external factors such as stress.

Frequently Asked Questions

Yes, it's very common for natural hair color to change with age. The most noticeable change is graying, which occurs as melanocytes (the cells that produce melanin) stop producing pigment. Hair can also darken or lighten slightly during childhood and adolescence due to hormonal changes and sun exposure, but significant shifts in underlying pigment type are rare after early adulthood.
While MC1R is the best-studied gene for hair color, many other genes play a role in determining the exact shade of black, brown, blond, or red hair. These genes control the overall levels of eumelanin (black/brown pigment) and pheomelanin (red pigment) produced, as well as how these pigments are distributed in the hair shaft. Examples include genes like ASIP, OCA2, and SLC45A2, which contribute to the complex spectrum of human hair colors.
Yes, it is entirely possible. Hair color inheritance is complex, and many genes are involved. For example, if both parents carry a recessive gene for red hair (like a variant in MC1R) but have dark hair themselves because they also have dominant dark hair genes, their child could inherit two copies of the recessive red hair gene and be born with red hair. Similarly, combinations of genes can result in lighter hair colors in children of dark-haired parents.
Red hair is primarily caused by an abundance of a pigment called pheomelanin, which happens when the melanocortin 1 receptor (MC1R) protein is deactivated or blocked. This deactivation is often due to specific variations in the MC1R gene. Yes, red hair is almost always inherited, typically as a recessive trait, meaning you need to inherit a copy of the variant MC1R gene from both parents to have red hair.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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