Is curly hair dominant or recessive? How DNA Affects Hair

Much of what you look like comes from a combination of your parents’ DNA. The texture and color of your hair is no exception. The genetic information embedded in your body creates a formula for the appearance of your hair throughout your life. Other factors, like nutrition, health issues, and hormones, have less of an impact than the DNA you were born with.

If both of your parents were born with curly hair, chances are you were also born with curly hair. But there are cases when two parents with curly hair can produce a child with straight or wavy hair.

Curly hair is considered a “dominant” genetic trait. Straight hair is considered “recessive”. Simply put, this means that if one parent gives you two curly-haired genes and the other parent gives you a straight-haired pair of genes, you will be born with curly hair.

Both of your parents give you two genetic pieces of information, called alleles, that determine what your hair type will be. The two alleles from your biological father combine with two alleles from your biological mother, giving you four in all.

Typically, a dominant gene is one that dominates a recessive gene when two different characteristics are present in the same piece of DNA. The dominant gene will become the visible trait in the person born with both characteristics in their DNA. A recessive gene is genetic information that you cannot see but can carry.

Let’s say your dad has curly hair. This doesn’t mean that both of its alleles are for curly hair. Since curly hair is dominant, he may have been born with curly hair, but also carries an allele for straight hair.

Let’s also say your mom has straight hair. Maybe she inherited two alleles for straight hair. This would mean that you have three alleles for straight hair and only one for curly hair. You could very well be born with straight hair, or pass on the possibility of having straight hair to your children.

There is not necessarily a single gene which causes your hair to become curly. Your hair type is the result of combining the DNA of your parents, in addition to your ethnicity. Studies to suggest that people with different ancestral histories have different genes that are responsible for their hair type.

Some human traits and health issues are only determined by your mother’s DNA. These are called “Y-linked” factors because they are transmitted through the Y chromosome.

There are also traits and conditions related to your father’s DNA. These are called “X linked” factors because they are passed through the X chromosome. The appearance of your hair is neither Y nor X linked.

The only exception to this rule would be if you are suffering from a genetic health problem with symptoms that impact the appearance of your hair. In some cases, these genetic health problems can be linked to a single gene or to a single mutation within a single gene.

Being born with curly hair doesn’t mean your hair will have that texture for the rest of your life.

Hormonal changes

Hormones can influence the structure of your hair follicle at different times in your life. Researchers still don’t fully understand all of the scenarios that can cause this.

You may notice that your curly hair becomes thicker, heavier, or less curly during pregnancy, for example. You may see your hair become less curly if it becomes thinner after childbirth. Hormonal fluctuations during menopause can also change hair texture.


There is also the issue of your immediate environment. You may have lived in a humid climate your whole life, but you have moved to dry and cool mountains. The texture of your hair can look a little different with the change in elevation, humidity, and even the water you use to wash your hair.

Health conditions

Certain health conditions can change the appearance of the texture of your hair, permanently or temporarily. Alopecia can decrease the thickness of your hair, making it less wavy. Drugs and treatments like chemotherapy can also change the appearance of your hair.


Finally, there is the food you eat and the nutritional supplements you take. There is no magic food or vitamin that you can eat to make your hair look that certain. But pursuing and prioritizing your health by eating a varied, well-balanced diet and meeting all of your nutritional needs can make a difference in the appearance of your hair.

When you are healthier, your hair can appear shinier, fuller, and more natural, and your hair texture can vary accordingly.

Curly hair is determined by factors you inherit from your birth mother and birth father. There is not a single gene that determines the appearance of your hair. The appearance of your hair at birth is also a clue to the genetic information you would pass on to your own children if you had any.

While the texture of your hair may vary throughout your life, that doesn’t mean your DNA has changed. Factors like hormones, nutrition, and your environment can cause your hair fiber to become more curly or less curly throughout your life.

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