By LunaDNA Contributor
Hair colors are passed down through generations. Sometimes the colors are predictable, and sometimes, unexpected colors occur through a genetic mutation. Learn about the genetics of hair color.
Hair colors are a spectrum of hues that can range from white blond to coal black. Hair color is inherited, and many genes are involved in the process. Sometimes, unexpected hair color can occur in a child because of a genetic mutation. Some of the genes involved in hair color also influence eye color and skin color.
Hair color is the result of genetics. Learn about the genetics of hair color and what causes different hair colors in this guide.
How Is Hair Color Determined?
Two types of pigment, or melanin, determine hair color. An abundance of eumelanin colors hair black or brown, and an abundance of pheomelanin colors hair orange or red. Every hair color contains some amount of the darker pigment eumelanin. Low levels of eumelanin result in lighter hair, and higher levels result in darker hair.
The genes responsible for hair color are neither dominant nor recessive — it is a matter of which genes are turned on or turned off. The hair color produced depends on the amount and type of melanin produced by melanocytes (melanin-forming cells). If receptors on the surface of the melanocytes are active, they produce, eumelanin, the pigment responsible for brown or black hair. If the receptors are inactive or blocked, they produce pheomelanin, the pigment responsible for orange or red hair.
Jet-black hair has large numbers of tightly packed eumelanin. Red hair has large numbers of tightly packed pheomelanin. Blonde hair has both types of melanin, but in very small amounts and loosely packed. Variations lead to a wide range of shades within each hue. Hair color usually darkens as genes are turned on and off during childhood and puberty. Later in life, hair can turn gray and white as fewer pigment cells produce and store melanin. Gray hair has only a little pigment in it, while white hair has no pigment.
Is Hair Color Genetic?
Hair color is one of several physical traits that are genetic, or passed down through an individual’s DNA. Human DNA has millions of on and off switches along networks that control how genes function. Genes responsible for hair color come from both parents.
Although the genes passed down from a child’s parents determine hair color, variations can result in a child having a different hair color than both parents. The genetics of hair color is the result of many genes working together to control the amount and type of melanin. Large amounts of very dense eumelanin produce black hair. Moderate somewhat dense amounts result in brown hair. Very little and thinly dispersed amounts result in blonde hair. If you have mostly pheomelanin with a little eumelanin, red hair is the result. Additionally, a variation in the blond gene can lead to premature graying.
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Is Hair Color Inherited from Mother or Father?
Hair color comes from both parents through the chromosomes passed onto their child. The 46 chromosomes (23 from each parent) have genes made up of DNA with instructions of what traits a child will inherit. The results can be surprising. For example, black-haired parents can unknowingly each carry an unexpressed blond-hair gene that can pass to their fair-haired child. This explains why siblings can have different shades of hair.
What Does Your Hair Color Mean?
Hair color may be related to your ancestry. Darker hair is more prevalent among people in the southern hemisphere, and lighter hair is more common in the northern hemisphere. Darker hair is associated with areas of harsh sunlight, and lighter hair with areas of less sunshine. However, there are many exceptions due to genetics, migration of people, and other factors.
Black and Brown Hair
The most common hair colors around the world are black and brown, and it is estimated that over 90 percent of people have black or brown hair. Depending on the levels of pigment, colors range from an almost light-blond brown to dark black.
Blonde Hair
Blonde hair is produced by low levels of pigment (called eumelanin). Variation in the small amounts of eumelanin accounts for the wide range of blond shades, from platinum blond to dark golden blond. Many people with blond hair develop darker hair later in life. Natural light blond hair in adults is rare.
Red Hair
Red is the rarest hair color and is thought to be found in around 1 to 2 percent of people worldwide. In the Northern Hemisphere, 2 to 6 percent of people have red hair.
Red hair ranges from light strawberry blond to deep burgundy, depending on the amount of pheomelanin (red pigment) and eumelanin (brown/black pigment) is present. Auburn hair has a higher concentration of pheomelanin, while chestnut hair has more eumelanin.
Red hair has fascinated humans throughout history. In fact, the term “redhead” was first noted in the 16th century. In addition, frescos from ancient times depict Hades, the god of the underworld, as a redhead.
Over time, scientific discoveries have led to a deeper understanding of the genetics that affects hair color. As advancements in genetics and overall health are made, more discoveries will undoubtedly unlock the mysteries of who we are, where we’re from, and why people around the world come in so many shapes, sizes, and hair colors.
Luna is bringing together people, communities, and researchers to better understand life, including genetic traits like hair color. The more we come together to contribute health data for the greater good, the quicker and more efficient research will scale, and improve the quality of life for us all.
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