The Science Behind Hair Colors Genetics of Our Natural Hair Color
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However, the gene for MPB is actually passed down from both sides of the family. It may also skip generations and affect siblings (male or female) completely randomly. That means that your older brother may have the George Clooney hair while you are stuck with the Vin Diesel look, or visa versa. BUT, if most of the men on your mother’s AND your father’s side are bald, then you, your sons and brothers most certainly inherited the gene. The Tech Museum of Innovation at Stanford University provides a Q&A on the differences in hair texture among ethnic groups and another on the inheritance of hair texture. Plots show the densities for each hair color category in the UK Biobank (top) and 23andMe cohorts (bottom).
Supplementary Figure 9 Sex-specific prevalence of hair color categories in the UK Biobank and 23andMe cohorts.
It is now believed to be dominant over blond and you will likely pass it down to your offspring (that’s how two brunettes can give birth to a red-haired). The eumelanin in your hair is expressed more than the phenomelanin, and your hair may have a reddish hue that's masked by a stronger brown or black pigment. While it might seem easy to determine some of what you inherited from each of your parents (blue eyes, curly hair, slender body, …), it is often much more complicated than it appears. Not only the genes you inherited don’t always have the same effect on your phenotype (blue eyes vs. brown eyes), who you inherited them from can change the end result (full hair vs. baldness). This is called “imprinting” and it can make a difference in how specific genes affect you. With so many genes involved, accurately predicting a baby's hair color with absolute certainty remains elusive.
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“We would therefore expect these color variants — so-called polymorphisms — to be fixed somewhere in the female genome,” Professor Wolf said. If you're a man, you got your X chromosome— which either has or does not have the variation of this gene that promotes baldness—from your mother. There's a 50% chance that she got it from her father—so if your maternal grandfather is bald, there are chances you will be too. However, dominance does not mean that one allele completely shuts down the other; both are active. That’s how your mother could have passed on the blue eyes gene while she has brown eyes (brown is dominant, she carries blue without expressing it).
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Human hair in brown color is seen in many shades like brown-ebony, brown-mahogany, brown-oak, etc. These many shades of brown are due to the presence of an allele, a specific variation in the gene that is found at the specific spot on the chromosome. For example, people with brown-ebony shaded hair have some alleles that catalyze the enzymes to produce a large amount of brown pigment. Some alleles in people with brown-Swedish blond suppress the enzyme production, which in turn causes less production of brown pigment. Based on this allele-enzyme activity, the shade of brown hair color differs.
For the most part the idea of a single brown/blond gene matches how hair colors are really passed down. If you add in a second gene with a recessive allele that makes red hair you’ve got a decent model of most hair colors and a nice story to go with it. In both cohorts, there is a higher prevalence of blond, red and light brown hair colors among women and a higher prevalence of black and dark brown hair colors among men. In contrast, there are many genes across our genome involved eumelanin variation, including less damaging genetic variants in the same MC1R gene.
To understand how baby hair color works, you will need to understand some basic genetics. Your genetic code consists of tens of thousands of directions that tell your body how to grow, called genes. Genes are stored inside chromosomes and determine everything from blood type to biological sex to a baby's eye color to a baby's hair color.
His work is globally published and he is quoted on top health platforms like Medical News Today, Healthline, MDLinx, Verywell Mind, NCOA, and more. Using his unique mix of genetics expertise and digital fluency, Dr. Sumeet inspires readers toward healthier, more informed lifestyles. Both overactive and underactive thyroid can affect the color in natural hair, making it dry and dull.
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Constant (monthly or six-weekly) maintenance is essential to match new hair growing in to the rest of the hair, and to remedy fading. A one-color permanent dye creates a flat, uniform color across the whole head, which can look unnatural and harsh, especially in a fair shade. To combat this, the modern trend is to use multiple colors—usually one color as a base with added highlights or lowlights in other shades.
Environmental Factors
One factor that complicates a forensic test for hair colour is the common tendency for children who are born blond to have their hair turn brown a handful of years later. While that change itself could well be driven by genes, the researchers found none that seemed to explain the effect. “We know that some blond kids become brown but we have no idea why that is,” said Manfred Kayser, a senior author on the paper at Erasmus MC. White-haired people reflect light due to the optical activity of the color.
Since it is found in dopamine neurons, it colors some areas of the brain, which has no direct relation with hair color. Mutation of neuromelanin may result in a neurodegenerative disorder, which has an indirect relation with hair color. The genome-wide association studies (GWAS) has found that the mutant gene that is responsible for blondness in the Northern European population is KIT ligand (KITLG), which has an ability to fight skin cancer.
If you want to predict hair color of your child, here is a simplified hair color calculator based on genetic predictions. The calculation and plot were made using the .ped and .map plink files, and plotting was performed using ggplot2 in R. The intricate genetic tapestry that determines hair color remains a captivating puzzle. In other words, there are limits to the predictability of genetics. However, external factors like sun exposure, particularly ultraviolet radiation or UV radiation, can also exert influence.
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The science of our color can be explained by a little bit of physics and a lot of biology and chemistry. While the absorption and reflection of light also determine the hair color, the primary factor to determine our basic hair color is by our Genes. As mentioned above, the type and amount of melanin pigments in our hair gives a color. The total amount of melanin and the ratio between eumelanin and pheomelanin is unique to us and entirely determined by our genes. However, it is not just a single or a couple of them, interestingly, several genes are involved in melanin production, and that can, therefore, affect our hair color. These genes switch on and off at different points in our lives – hence the reason our hair changes color as we get older.
Black eumelanin secretion causes the hair to turn black, which indicates that the MC1R is in the active state. Lack of nutrients like vitamin B12, iron, and copper can lead to dull and lifeless hair. Changes in hair color due to hormonal fluctuations during life events like pregnancy or menopause are typically temporary.
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