Curly hair is a dominant genetic trait, meaning you're more likely to have curls if one or both parents do, but it's complex, involving multiple genes and influencing factors like follicle shape (oval for curly, round for straight), and genetics aren't perfectly predictable, with wavy or straight hair possible even with curly-haired parents.
The genes for curly hair and straight hair are both considered dominant, and the phenotype (what is physically displayed) of wavy hair is an in between of the dominant phenotypes. This is an example of something called incomplete dominance. So imagine a gene H.
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.
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.
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.
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.
Asian hair generally exhibits the strongest mechanical properties, and its cross-sectional area is determined greatly by genetic variations, particularly from the ectodysplasin A receptor gene.
Every cell we have descends from a the first human cell, a zygote. And zygote mitochondria comes only from egg cells, never from sperm cells. So every gene that belongs to us from mitochondria is only inherited from our mom's side. So, taking this into account, you could say that we have more mom genes than dad genes.
Both parents contribute genes that influence hair color, and the outcome is a result of their combined genetic makeup. Another myth is that dominant genes always determine hair color. Hair color inheritance is more complex than a simple dominant-recessive pattern.
Type 1A Hair
This is considered the rarest hair type because it lacks any natural bend. People with 1A hair often find it difficult to hold curls, even with heat styling. The advantage of this hair type is its naturally sleek appearance, but it requires careful handling to prevent breakage.
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.
As we age, hormonal shifts, slower cell regeneration, and changes in the hair's internal structure (like the production of keratin and sebum) can all contribute to curls loosening, tightening, or becoming less defined. Your hair, like your skin and body, evolves with time.
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.
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 controlled by multiple genes. However, both parents need a curly gene to have a curly child. The type of curl (2A to 4C) depends on the combination of these genes and what each parent contributes.
Fathers will always pass their X chromosome to their daughters and their Y chromosome to their sons.
Height inheritance is typically equal from both parents, with each contributing approximately 50% of the genes that influence height.
Intelligence genes are situated on the mother's X chromosome. Thus, an intelligent mom has intelligent kids even if their fathers aren't wise. Scientists from the University of Cambridge conducted this study. The 'conditioned genes' behave differently depending on their origin.
“The ethnicity with the least amount of terminal hair is Asian, whereas people of Hispanic and Middle Eastern descent typically have the most. Other ethnicities fall somewhere in between. So what's normal, hair-wise, for you might not be normal for someone of a different ethnic background.”
Asian hair has the highest hardness and elasticity. It is resistant to stretching and can withstand a traction force of 60 to 65 grams.
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.
The texture of curly hair adds body and volume, creating a look that is hard to resist. Finally, men are attracted to curly hair because it is unique and eye-catching. Curly hair stands out in a crowd and can be a great conversation starter. It is also a great way to express your personality and creativity.
The table below presents data-driven estimates of curly hair prevalence across several countries. South Africa and Brazil top the list with the highest percentages, while Japan and China record the lowest, highlighting the vast global diversity in hair texture.
We confirm that scalp hair reduces heat gain from solar radiation and find an effect of hair morphology. Our results show that tightly curled hair provides the most effective protection for the scalp against solar radiation, while minimizing the need for sweat to offset heat gain.