What Determines Hair Color

In order to design the best hair color products, it’s important to understand the natural hair color we were born with. Although there is a wide range of hair colors that occur naturally—platinum blond, jet black, auburn red—there are only two pigments that determine hair color. These pigments, eumelanin and pheomelanin, play a significant role in how hair colors are determined. Everyone has the pheomelanin pigment in his or her hair, which creates orange and red hair color. The levels of black or brown eumelanin determine how dark hair will be and what hair color is dominant. As one might expect, low concentrations of the eumelanin pigment will yield blonde hair, while high concentrations result in darker brown hair. People with natural red hair have much higher pheomelanin levels in their hair than people with more common hair colors like brown, blonde, and black.

As with a lot of things we’re born with—eye color for example—genetics are also an important part of understanding what determines hair color. Current genetic theories suggest that at least two gene pairs control human hair color. One of these explores the brown or blonde hair possibilities. Brown hair is dominant, and blonde hair is recessive. When a person has both brown and blonde alleles in their genes, he or she will have brown hair. If a person has no brown alleles, he or she will be blonde. Although there is a lower likelihood that a child with two brown-haired parents will be blonde, it is possible when the parents contain recessive alleles because they are passed to their offspring.

The other gene pair that helps determine hair color is the non-red and red model. The non-red allele is dominant, while the red allele is recessive. Similar to how a person will have blonde or brown hair, if a person has a non-red allele, he or she will not have red hair. The absence of the non-red allele will yield red hair. Much like a blonde child with two brown-haired parents, it’s possible for a child to have red hair even if his or her parents do not. You might have heard that “red hair skips a generation.” While that’s not a precise genetic rule, it is often used as a way to explain where a child’s red hair came from—often from a grandparent.

Although this two-gene model helps to explain how we get the hair color that we are born with (brown, black, blonde, red), it doesn’t explain the varying shades of each hair color—take for example, the range of blonde hair from platinum to dark blonde, or how some people experience darkening hair color from childhood into adulthood. These shade differences are controlled by several different gene pairings, a person’s genotype, and environmental surroundings.

Understanding hair pigments and shade ranges helps us target hair color that communicates with one’s natural hair color, while enhancing it to look its best. Our color advisor is a great way to start your hair color journey, and will help you choose the shade that best compliments what you are already working with. Put simply, we know how hair color works, from the inside out.

Another important part of our work at Madison Reed is not only understanding how hair color works, but also how hair grows. All hair, not only just what comes from our scalps, grows out of small pockets in our skin called follicles. The process is explained below:

Our hair grows quickly too—it’s the second fastest growing part of your body. Only bone marrow grows faster. Although there is some variance between each person, hair would grow approximately six inches per year if left untrimmed. This means that hair grows about a half inch per month, which helps to determine how frequently to color your roots, if you choose to color your hair.

You may notice some strands of hair on your brush or on the shower floor. Although this can be alarming, it’s important to remember that it’s normal to lose between 50 and 100 strands of hair each day. This occurs because our follicles are not all working at the same time. Each follicle grows hair for a few years at a time and then takes a break, while other follicles resume growth. When the follicle stops working, the hair within it falls out. As we age, some follicles simply stop growing hair. This contributes to later-in-life hair loss or balding, often in men.