Curly hair is genetic, influenced by several genes, primarily variations in the TCHH (trichohyalin) gene, which produces proteins that link keratin fibers, causing asymmetrical cell growth in oval-shaped hair follicles, leading to curls. While TCHH is key, other genes like EDAR and FGFR2 also play roles, and the exact combination of inherited genes determines your specific texture, not just one "curly hair gene".
Curly hair is most common amongst people with African, Mediterranean and Native American ancestry. There's a specific gene that helps shape the hair shaft and determine hair texture, and it's called trichohyalin. Curly hair is caused by a variation in the gene that determines the shape of our hair follicles.
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.
How the hair grows out of the follicle influences the distribution of its proteins. So a straight follicle produces straight hair and a curved follicle produces curly hair. The less evenly distributed the squiggly proteins are, the curlier the hair.
Around 11% of the global population has naturally curly hair, though the percentage is much higher in certain regions like Africa and Latin America. The shape of the follicle determines curl pattern — the more oval the follicle, the curlier the hair.
The rarest hair type is generally considered Type 1A, which is extremely fine, straight, and wispy, lacking any natural bends or waves, making it difficult to hold a curl but naturally sleek and prone to oiliness. While curly hair types (Type 3 & 4) are less common globally, 1A stands out as the least voluminous and textured straight hair, often seen in people of East Asian descent, though it's considered rare across all populations due to its unique fineness.
The gene for curly hair in Caucasians
It has been long established that curly hair is a dominant trait in Caucasians and straight hair is recessive.
Individuals of African ancestry, for example, are more likely to have curly hair due to the oval shape of their hair follicles. Additionally, the Keratin Associated Protein (KAP) cluster genes, responsible for the structure of keratin fibers, have been found to have variations in many African populations.
Tightly curled hair better protects the scalp from solar radiation, the new research shows, and it doesn't lie flat against the skin while wet—a boon in hot conditions that can make humans sweat, like those encountered by our hominin ancestors in Africa millions of years ago.
Your biological father can pass on physical traits such as your biological sex, eye color, height, puberty timing, fat distribution, dimples, and even risk factors for certain health conditions.
Curly hair is considered a “dominant” gene trait, meaning if one of your parents had curly hair, they gave you two curly-haired genes, and you're more likely to have curls.
Wavy hair (2A to 2C) is the most common, representing 40% of the US population! 🌊 Next up is straight hair (1A to 1C), making up 35% of people. 💁♀️ Curly hair (3A to 3C) is the second most rare, with 15% of the population rocking those beautiful curls!
While curly hair is dominant, and you are likely to have curls if one or more parents have curly hair, it doesn't always work this way, as one of your parents' alleles could be encoded with a straight hair gene they pass to you.
Busting the Myth
Ultimately, hair loss isn't as simple as inheriting it from one side of the family. Instead, it's a blend of genetic influences that come from both parents.
The Curly Hair Theory is the idea that curly hair behaves differently from straight hair because of its structure, follicle shape, and chemical bonds. It's not just a style - it's a science. Here's the science made simple: Curly hair follicles are oval or asymmetrical, which makes strands bend and spiral as they grow.
You're blessed with natural volume and texture
Another boon of curly hair is that, unlike others, we don't have to create volume. Our tresses always appear volumized and textured.
Japan, Spain and Sweden are widely known for having people with healthy hair, but there are also other countries like India, France and Russia that are also known for helping people keep their hair natural and not messing with any artificial coloring.
What Ethnicity Has The Highest Hair Density? Caucasians have the highest hair density.
Type 1A is the rarest hair type and is stick-straight without even a hint of a wave.
Curly hair has for centuries always been linked to individuals of Middle Eastern and African ethnicity. We find it interesting that such a generalisation can be made as there are always exceptions to every rule. Let's uncover the truth.
Factors such as decreased melanin production, loss of moisture, and structural changes in the hair follicles contribute to the wiry texture commonly associated with grey hairs.
In straight type, thin hair was judged most attractive, whereas in wavy type, hair with mean diameter received the highest attractiveness judgments. In conclusion, there was considerable variation in age, health and attractiveness perception of hair with regard to effects of hair diameter, type, and color.
Red hair is the rarest natural hair color in humans. The non-tanning skin associated with red hair may have been advantageous in far-northern climates where sunlight is scarce.
Long scalp hair is likely to have evolved first as long, tightly curled hair for better thermoregulation and was further selected at a later point in human evolution owing to its unique social communication functions.