Is Curly Hair Genetic? How DNA Affects Your Hair Type

The curly girl method took the internet by storm and became a much-needed blessing for all those flaunting their gorgeous curls. It has helped enhance the look of the natural curls for many. But the hair products are definitely not the roots of curly hair. Your hair texture is predominantly genetic, and the curly hair gene is more dominant than the straight hair gene.

The Different Hair Types

Understanding your hair type helps explain how genetics influence your locks. Hair is commonly categorized using the Andre Walker Hair Typing System, which ranges from Type 1 (straight) to Type 4 (coily). Here's a simple breakdown:

Different Types Of Hair Patterns
Type 1: Straight Hair Straight hair is smooth and lacks any natural curl or wave. It's known for its sleek appearance and ability to reflect light, giving it a shiny look.
1A	Very straight and fine, with little volume or body
1B	Straight but with more texture and medium thickness
1C	Straight with coarse strands, prone to slight waves and frizz
Type 2: Wavy Hair Wavy hair sits between straight and curly hair types. It has an "S" shape and can range from loose, subtle waves to more defined ones.
2A	Soft, loose waves with a fine texture
2B	Defined "S"-shaped waves, more prone to frizz
2C	Deep waves nearing curls, thick and resilient hair
Type 3: Curly Hair Curly hair forms distinct loops and spirals. The curls can vary from loose rings to tight corkscrews.
3A	Large, loose curls about the size of sidewalk chalk
3B	Bouncy ringlets similar in size to a marker
3C	Tight curls the diameter of a pencil, voluminous and springy
Type 4: Coily Hair Coily hair, also known as kinky or afro-textured hair, features tight curls in a zigzag pattern. The strands are densely packed and can shrink significantly when dry due to the tight curl pattern.
4A	Dense, spring-like coils about the size of a crochet needle
4B	Z-shaped coils with sharp angles and less defined patterns
4C	Tightly coiled with minimal definition, highly prone to shrinkage

What Aspects of Hair are Genetic in Nature?

Genetics plays a crucial role in determining various characteristics of your hair. Here are some key aspects influenced by your genetic makeup:

1. Hair Texture and Type

The shape of your hair follicles—determined by genetics—largely dictates whether your hair is straight, wavy, curly, or coily. Round follicles produce straight hair, while oval or twisted follicles result in wavy or curly hair.

2. Hair Color

Natural hair color depends on the type and amount of melanin pigments. Genes influence whether you have more eumelanin (leading to black or brown hair) or pheomelanin (resulting in red or blonde hair).

3. Hair Thickness and Density

Genetic factors determine the thickness of individual hair strands and the overall density of hair follicles on your scalp.

4. Hair Growth Rate and Length

The rate at which your hair grows and its maximum potential length are genetically predetermined. Genes influence the duration of the anagen (growth) phase of the hair cycle, affecting how long your hair can grow.

5. Hair Loss and Pattern Baldness

Conditions like androgenetic alopecia (male or female pattern baldness) are influenced by genetics. Specific genes can make hair follicles more sensitive to hormones like dihydrotestosterone (DHT), leading to gradual hair thinning and loss.

6. Graying of Hair

The onset of graying is also genetically controlled. Genes affect the decline in melanin production over time, which causes hair to lose its color and turn gray or white.

Is Curly Hair Genetic?

Yes, curly hair is genetic - however, there’s no one single gene responsible for it.

The genetics behind hair curliness is complex and multifactorial.

Several genes have been implicated in determining hair texture, but a prominent one that has been studied in relation to hair curliness is the TCHH (trichohyalin) gene.

The protein produced by the TCHH gene plays a role in the development of the hair shaft.

It is localized in the inner root sheath of hair follicles.

Variations or differences in this gene have been associated with the difference in hair curliness across populations.

A 2009 study identified a genetic variant in the TCHH gene that is responsible for 6% of the variance in curly, wavy, and straight hair.

However, it's essential to understand that the presence or absence of this variant doesn't guarantee straight or curly hair but rather influences the odds.

Other genes like EDAR and FGFR2 have also been linked to hair texture.

The interplay between multiple genes, each with its variants, determines the final hair phenotype, making the genetics of hair curliness a complex trait.

Is Curly Hair Dominant or Recessive?

Curly hair, from a genetic standpoint, tends to be a dominant trait.

Dominant traits are those that overpower recessive ones. Dominant traits need only a single copy from either biological parent to be expressed.

On the other hand, recessive traits need two copies, one from each biological parent, to be expressed.

Straight hair is a recessive trait.

However, like many genetic traits, hair type isn’t a straightforward dominant or recessive game.

If both parents have a combination of genes (one for straight and one for curly hair), their offspring can exhibit a range of hair textures.

Even within families with a strong prevalence of curly hair, hair type could vary significantly, emphasizing the complex interplay of genes.

Did You Know?

Not just hair, but many aspects of your skin, from the risk for premature wrinkles and acne to your ideal skincare routine, are influenced heavily by your genes! Your ancestry test DNA data includes 700,000 markers, which can be used to learn in-depth about your skin aging and skin health. This report will help you understand your skin requirements better and aid in graceful aging. Learn more.

Is Curly Hair Rarer Than Straight?

Some reports say that less than 20% of the world’s population have proper curly hair, making it rarer than straight or wavy hair.

What is the Rarest Curl Type?

The hair spectrum includes rare types like Type 1c (straight and thick) and Type 4c (tight coils with zigs and zags).

The prevalence of these types varies by ethnicity and region.

Beyond Genetics: Environmental and Lifestyle Factors

Genetics lays the foundation, but environment and lifestyle choices build upon it.

Hormonal changes, nutritional choices, stress, and even hair care routines can shift hair texture over time.

For instance, prolonged exposure to humidity or salty water can influence hair’s texture.

Prolonged heat treatments or chemical applications can lead to a permanent change in hair type.

Additionally, hormonal fluctuations, especially during pregnancy or menopause, can lead to hair texture modifications.

Other FAQs On Curly Hair Genetics

Can I Have Curly Hair If My Parents Don’t?

While genetics favor curly hair offspring, if one or both parents possess curly hair, it isn’t absolute.

Genes can sometimes skip generations.

So, even if your parents do not have curly hair if someone in the previous generations did, there’s a chance of you having curly hair.

Which Parent Gives Curly Hair?

Both parents contribute genes, so neither parent singularly determines curly hair.

It’s the combination of genes from both that paints the final picture.

Can Two Straight-haired Parents Have a Curly-haired Child?

Absolutely. The mystery of genetics means that if both parents carry the recessive curly hair gene, their child could very well sport a curly mane.

How Rare Is Naturally Curly Hair?

Naturally, curly hair is relatively common but varies by population and ethnicity.

Globally, it's estimated that about 11% of people have naturally curly hair.

The prevalence can be higher or lower in specific regions due to genetic diversity and ancestral backgrounds.

What Ethnicity Does Curly Hair Come From?

Curly hair is found across all ethnicities, though its prevalence and type can vary.

It is common among people of African descent, who often have tightly coiled hair.

Wavy and curly hair types are also prevalent in Middle Eastern, European, South Asian, and Latin American populations due to diverse genetic backgrounds.

Summary

Our hair's texture, whether curly or straight, often prompts the question: "Is hair type genetic?" Delving into the science behind our locks reveals that genes, such as TCHH, play a crucial role in shaping our hair's form, confirming that curly hair is genetic. While genetics typically suggests that curly traits tend to dominate, it's not the sole influencer. Environment and lifestyle choices weave into the narrative, adding depth to the story of every curl and strand.