Is Curly Hair Dominant or Recessive? How DNA Affects Hair (2023)

Much of what you look like comes from a combination of your parents’ DNA. Your hair’s texture and color are no exception. Genetic information that’s embedded in your body creates a formula for what your hair is going to look like throughout your lifetime. Other factors, like nutrition, health conditions, and hormones, have less impact than the DNA that you’re born with.

If both of your parents were born with curly hair, chances are that you’ll be born with curly hair, too. But there are cases where two curly haired parents can produce a child with straight or wavy hair.

Curly hair is considered a “dominant” gene trait. Straight hair is considered “recessive.” To put that in simple terms, that means that if one parent gives you a curly-haired gene and the other parent gives you a straight-haired gene, you’ll be born with curly hair.

What makes genes dominant or recessive?

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Both of your parents give you two pieces of genetic 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 overpowers a recessive gene when two different characteristics are present in one 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 a piece of genetic information that you can’t see, but that you may carry.

Let’s say that your father has curly hair. That doesn’t mean that both of his alleles are for curly hair. Since curly hair is dominant, he may have been born with curly hair but carry an allele for straight hair, too.

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

There isn’t necessarily one single gene that causes your hair to become curly. Your hair type is the result of how your parent’s DNA combines, in addition to your ethnicity. Studies suggest that people with different ancestral histories have different genes that are responsible for their hair type.

There are some human traits and health conditions that are determined by the genes passed through the sex chromosomes (X and Y chromosomes). These are called sex-linked traits. The way your hair looks is neither Y-linked or X-linked.

The only exception to this would be if you have a genetic health condition with symptoms that impact the way that your hair appears. In some cases, these genetic health conditions may be linked to a single gene or a single mutation within a single gene.

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

Hormonal changes

Hormones can influence your hair follicle structure at different points of your life. Researchers still don’t completely understand all of the scenarios that can cause this to happen.

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 thins out postpartum. Hormone fluctuations during menopause may also cause hair texture to change.

Environment

There’s also the matter of your immediate environment. Maybe you’ve lived in a humid climate all of your life but move to the dry, cool mountains. Your hair’s texture may look a little different with the change in altitude, humidity, and even the water you’re using to wash your hair.

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Health conditions

Certain health conditions can change the way that your hair texture looks, permanently or temporarily. Alopecia can diminish the thickness of your hair, making it appear less wavy. Medications and treatments like chemotherapy can also change the look and feel of your hair.

Nutrition

Finally, there’s the food that you eat and the nutritional supplements that you take. There’s no magic food or vitamin that you can consume that will make your hair look a certain way. 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 how your hair looks.

When you’re at your healthiest, your hair may look shinier, fuller, and more natural, and your hair’s texture may vary accordingly.

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Takeaway

(Video) 77 - Determining Inheritance - Curly Hair (p61)

Curly hair is determined by factors you inherit from your biological mother and your biological father. There’s no single gene that determines the way that your hair looks. The way your hair looks when you’re born is also a clue into the genetic information you’d pass to your own children if you have them.

While your hair texture may vary throughout your life, that doesn’t mean that your DNA has changed. Factors like hormones, nutrition, and your environment can make your hair fiber appear more curly or less curly throughout your lifetime.

FAQs

What gene affects curly hair? ›

There is evidence that trichohyalin (TCHH) may affect hair curl in most/all world populations and that other genes such as EDAR and WNT10A only affect specific populations. Hair curl variation in native Africans is very likely a complex trait with multiple genes influencing curl.

What DNA makes curly hair? ›

So for hair type, CC gives curly, Cs gives wavy and ss gives straight hair. Back to your specific situation. As you can probably tell, the couple you describe could only have wavy haired kids. That is because the curly headed parents, CC, can only contribute a C gene and the straight haired parent, only an s gene.

Is curly hair gene more dominant? ›

Curly hair is dominant, so someone is more likely to have curly or wavy hair if at least one of their parents does. Recent research points to trichohyalin, a protein in hair follicles, as having primary influence over hair curl. However, there are many genes contributing to hair curliness, most of them unknown.

Where does the gene for curly hair come from? ›

The story of human migration and evolution is written in hair DNA. In sub-Saharan Africa, genes favour tight, curly hair. But in east Asia, mutations have led to straighter, thicker hair. In Europe, other mutations brought wavy and straw-coloured hair.

Is curly hair the stronger gene? ›

Curly hair is considered a “dominant” gene trait. Straight hair is considered “recessive.” To put that in simple terms, that means that if one parent gives you a curly-haired gene and the other parent gives you a straight-haired gene, you'll be born with curly hair.

How rare is naturally curly hair? ›

Lots of traits are statistically rare: Left-handedness (just 10 percent of the population!), curly hair (11 percent!), and blond hair (4 percent!), to name a few.

Is there an evolutionary reason for curly hair? ›

However, in some climates certain hair types might be advantageous, for example very thick curly hair is a better protection against strong sun. In other areas where the sun is not so strong hair type would be irrelevant to survival and reproduction.

What race carries curly hair? ›

Curly hair is not certain to a race or ethnicity, it appears all over the world in many forms. White, brown, black and everything inbetween! There is also a scale on which curly hair is classified (2a-4c).

Is being curly hair rare? ›

Yes, only 11% of the population have curly hair.

Can curly hair skip a generation? ›

So, while curly-haired parents tend to have curly-haired kids, there's no guarantee it will happen. Because many different genes are involved, even a curly-haired parent can have—and pass along—straight-hair gene variations.

Is hair inherited from mother or father? ›

One popular myth is that hair loss in men is passed down from the mother's side of the family while hair loss in women is passed down from the father's side; however, the truth is that the genes for hair loss and hair loss itself are actually passed down from both sides of the family.

Why do I have curly hair but my parents don t? ›

It could be that neither of your parents have curly hair, but an ancestor did. Then the curly hair gene could have been passed down through generations and your parents are carrier of that gene, which manifested its trait in you!

What determines if you have curly hair? ›

Follicle Shape- The shape of your hair follicle largely determines your curl. Oval follicle shapes produce curly hair while round follicles produce straight hair.

What ethnicity has the thickest hair? ›

Caucasians have the highest hair density among the ethnicities studied. Black people have the lowest. Asian people have hair density that falls somewhere in between.

What is the rarest hair texture? ›

Hair type 1A is super-straight. It doesn't even hold a curl! 1A is the rarest hair type. It is usually found on people of Asian descent.

How rare is super curly hair? ›

Yes, only 11% of the population have curly hair.

Is curly hair more prone to balding? ›

All things being equal, there's no evidence that there's any difference in the natural cycle of hair loss for people with either straight or curly hair. We all shed hair at various times in the hair growth cycle but having straight or curly hair doesn't have much of an impact either way.

Is curly hair more prone to damage? ›

The curlier the hair, the more likely it is to have weak cross-sectional points that make it vulnerable to breakage and heat damage.

What is the most curly hair type? ›

Out of all the hair types, types 4A, 4B and 4C are the curliest. They tend to form a compacted Z pattern, plus they have a high density that requires creams, gels and custards to hold their shape and reduce volume. Plus, due to the lack of cuticle layers, coily hair also requires extra moisture.

What of the world has naturally curly hair? ›

According to msn.com, only 11 per cent of the world's population has curly hair. And only 4 per cent of the world is blond haired.

Is curly hair weaker than straight? ›

Curly hair is a bit more delicate than straight hair, and the tighter the curl or coil, the more fragile the strand. Curls generally need a little extra love, and it's important to know how to do right by your hair so it can stay looking amazing.

What does having curly hair symbolize? ›

Curly hair is often associated with a fun-loving, warm hearted and outgoing personality. If you have curly hair you are perceived as being courageous, outspoken, and spontaneous.

Is curly hair a Caucasian trait? ›

Can Caucasian people have curly hair? Human hair comes with all sorts of colors, textures and shapes. Notably, African hair is more coiled and dry; Asian hair is straighter and thicker; and Caucasian hair is somewhere in between with around 45% having straight hair, 40% having wavy hair, and 15% having curly hair.

Why do only Africans have curly hair? ›

Follicles that are more oval in shape cause curlier hair to grow. Very tightly coiled hair is due to the nearly flat, ribbon-like structure of their follicles. This hair texture is very common in people of African ancestry. Not only is African hair often coiled, it also has a unique texture.

Why do some Caucasians have curly hair? ›

It's a mutation in the gene that causes curly hair. I am 100% Scottish and I have very curly hair. My sister has even rarer pin straight hair. Roughly 45% of Europeans have curly hair gene even if they don't present curly hair.

Where does black curly hair originate from? ›

Afro-textured hair, or kinky hair, is a human hair texture originating from sub-Saharan Africa. Each strand of this hair type grows in a tiny, angle-like helix shape.

Can two straight haired parents have a curly haired baby? ›

it's very unlikely because none of you hold the dominant curly haired gene. You both may have recessive curly haired genes if both your direct family members have curly hair, but even then it's more so unlikely.

Is curly hair harder to grow? ›

The fact of the matter is that curly hair takes a longer time to grow longer because it grows in a curl, rather than straight down. But curly hair, as well as straight hair, usually grows about 1/2” per month. So with patience, and with a coordinated plan with your hair stylist, you can have longer hair.

Do curly people go bald? ›

Contrary to popular belief, there's no real difference between straight hair and curly hair when it comes to hair loss. Since hair loss is primarily caused by hormonal, genetic, health or environmental factors, the type of hair you have doesn't significantly impact your risk of experiencing hair loss.

Why is my curly hair not curly anymore? ›

Curly hair is delicate and can become dry, brittle and ultimately less curly with thermal styling. Over-manipulating, or wearing tight protective styles can also cause your curl pattern to change. In fact, even your go-to ponytail may be what's stretching your hair and affecting your curl pattern and texture.

Why does curly hair make you look younger? ›

Women with curly, textured hair tend to look younger than straight-haired counterparts as they age. Because of the natural volume that comes with having curly hair, thinning is less noticeable. Consider your frizz and volume to be a blessing in disguise! Are you looking for a new young, fresh look for fall?

Why was my hair curly as a kid but now straight? ›

Drastic hormonal changes or medical treatments like chemotherapy can also change the muscles in your hair follicles and cause new hair patterns to emerge. Hormonal changes around puberty can also affect your hair's texture.

Why was I born with curly hair but now it's straight? ›

Others have curls and straighten them out. But for a few people, their hair actually changes shape and texture on its own — and not just because of the weather. Scientists don't know exactly why this happens, but it probably has to do with a combination of genetics, hormones and body chemistry.

What genes are inherited from father only? ›

All men inherit a Y chromosome from their father, which means all traits that are only found on the Y chromosome come from dad, not mom. The Supporting Evidence: Y-linked traits follow a clear paternal lineage.

Which parent determines hair thickness? ›

Hair thickness is an “additive" trait. This means that if you inherited two copies of the “thick hair" version of the gene (one from each parent), you'll likely have even thicker hair strands than if you only inherited the "thick hair" version from one parent.

What genes are inherited from mother only? ›

Unlike nuclear DNA, which comes from both parents, mitochondrial DNA comes only from the mother.

Can curly hair turn straight after puberty? ›

In both sexes, these hormones contribute to increased body hair and, later, balding in males. An increase in androgens in females can actually change the shape of the hair follicle from round to flat and this can instigate a change in texture from straight to curly.

How do you activate curly hair gene? ›

Can you activate the curly hair gene? People who have a curly-haired parent assume that they can activate this gene. If by puberty your hair doesn't turn curly then you can't activate a curly hair gene.

What protein makes hair curly? ›

When hair moves through round follicles, it gets evenly coated with a protein called keratin. Keratin is what gives human hair structure. Hair that grows through oval follicles tends to have more keratin on one side than the other. As a result, it curls.

What race hair grows the fastest? ›

Asian hair shows the fastest growth rate in comparison to the other two hair types. African hair has the lowest growth rate.

What race has less hair? ›

Certain races have higher rates of hair loss compared to others. Caucasians have the highest rates out of all the ethnic groups. On the opposite end of the spectrum, Native American Indians, Inuits, and Chinese have the lowest rates. Let's dive in deeper.

What race has frizzy hair? ›

The African hair is generally curly or frizzy, and grows almost parallel to the scalp. It has the slowest growth rate of 0.9 centimeters per month due to its spiral structure which causes it to twist on itself as it grows. African hair has a flattened shape.

What is the strongest hair type? ›

Thick (Coarse)

Thick or coarse hair texture is the strongest hair texture and typically feels coarse or thick to the touch. Coarse hair contains all three hair layers – the cortex, cuticle and medulla.

What is considered the prettiest type of hair? ›

A general observation across experiments was that straight hair was perceived as younger, healthier, and more attractive than wavy hair and darker shades (medium copper and brown) were perceived more positively than blonde hair.

What is the rarest combination hair and eyes? ›

The title of rarest hair colour/eye colour combination belongs to red haired folks with blue eyes. According to Medical Daily, both the blue eye trait and the red hair trait are recessive, so their likelihood of simultaneous appearance is pretty slim.

What chromosome determines curly hair? ›

The scientists, from the Genetic Epidemiology Laboratory at the Queensland Institute of Medical Research (QIMR) in Brisbane identified the TCHH gene (trichohyalin) on chromosome one as the major gene controlling the curliness of hair.

What genotype is curly hair? ›

We can call the straight hair allele “S” and the curly hair allele “C.” Everyone has two copies of the hair texture gene. Their genotype will determine what kind of hair they have.

What hormone gives curly hair? ›

An increase in androgens in females can actually change the shape of the hair follicle from round to flat and this can instigate a change in texture from straight to curly.

Is it rare to have curly hair? ›

Hair morphology is one of the more conspicuous features of human variation and is particularly diverse among people of European ancestry, for which around 45% of individuals have straight hair, 40% have wavy hair, and 15% have curly hair.

What ethnicity has curly hair? ›

Curly hair is not certain to a race or ethnicity, it appears all over the world in many forms. White, brown, black and everything inbetween! There is also a scale on which curly hair is classified (2a-4c).

Does curly hair come from mom or dad? ›

Curly hair is determined by factors you inherit from your biological mother and your biological father. There's no single gene that determines the way that your hair looks. The way your hair looks when you're born is also a clue into the genetic information you'd pass to your own children if you have them.

What does curly hair symbolize? ›

Curly hair is often associated with a fun-loving, warm hearted and outgoing personality. If you have curly hair you are perceived as being courageous, outspoken, and spontaneous.

Why is African hair curly? ›

Follicles that are more oval in shape cause curlier hair to grow. Very tightly coiled hair is due to the nearly flat, ribbon-like structure of their follicles. This hair texture is very common in people of African ancestry. Not only is African hair often coiled, it also has a unique texture.

What foods grow curly hair? ›

Top 10 Foods for Curly Hair Growth
  • PINEAPPLE.
  • AVOCADO.
  • ORANGE.
  • NUTS.
  • VEGGIES.
  • SALMON.
  • DAIRY.
  • WATER.
Sep 4, 2018

What protein causes curly hair? ›

When hair moves through round follicles, it gets evenly coated with a protein called keratin. Keratin is what gives human hair structure. Hair that grows through oval follicles tends to have more keratin on one side than the other. As a result, it curls.

What stimulates curly hair growth? ›

Here's some tips to stimulate hair growth and see results within weeks:
  • Growth Oils and Coffee. Stimulation and blood flow greatly help hair growth. ...
  • Split ends are NOT repairable. ...
  • Taking Vitamins and Eating Enough Protein. ...
  • Natural Food Masks (Or Protein Masks in General) Method.
Feb 13, 2018

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