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.
Fibres in the latter group were thicker, stronger and stiffer, with a greater scalp density. This means that curlier hair was found to be thicker, stronger and more resilient under mechanical forces than the near-straight hair.
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.
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.
Your hair is naturally voluminous
Curls adds volume to your hair effortlessly, and you never have to worry about it being flat, limp and lifeless like those with straight hair. Even on days when you straighten your curls, there is always going to be that little amount of volume that will make others go green with envy.
Yes, only 11% of the population have curly hair.
Less than 20% of people have naturally curly hair. The percentage gets even smaller when you consider the scores of guys out there who don't embrace their curls.
Coily Curls
The last, but most rare type of curl is the coily curl. This curl type is similar to that of an afro and when observed carefully, looks like the angular letter 'Z'. These curls require the most amount of moisture, as the hair type is much thicker than the other curl types.
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).
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 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. You are probably someone who likes to challenge perceptions and norms.
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.
In fact, more people prefer curly hair to straight hair. Though beauty is seen differently by everyone, one thing is for sure; curly hair is getting a lot of love lately. In fact, in a survey conducted by StyleCaster, a surprising 58% of guys thought curly hair was sexier than other hair textures.
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.
Hair Type and Hair Loss
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.
Fragility. Natural curly hair tends to be more fragile than straight hair. Due to the uneven shape of the hair fiber, the hair shaft can have “high spots” where the cuticle is slightly lifted compared to the rest of the hair fiber.
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.
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.
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.
Curly hair is vulnerable, the twists and turns in the structure make the cuticle weaker and also increase the amount of tangles. An exposed cuticle makes the hair more prone to damage, so make sure to use a heat protectant when you're doing any type of heat styling.
Over 60% of the world's population has curly hair, yet most research to date has clumped hair into three catchall types - African, Asian, and Caucasian.
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.
An estimated 65 percent of the U.S. population has curly, coily or wavy hair, with a growing percentage of textured-hair women embracing their natural hair .
Many Asians have naturally straight hair, but there is a significant group of us who do have naturally curly or wavy hair! However, because it's the norm to see straight and sleek hair, curly haired boys and girls tend to think that their hair is some kind of unruly straight hair that isn't behaving.
Puberty, menopause and pregnancy all cause hormonal shifts that can make your tresses go from straight to curly hair. In fact, 40-50% of women experience major changes in their hair while pregnant or breastfeeding.