One Gene, Three Hair Types: Meet EDAR
By MyGeneLog™ Team · September 24, 2026 · Pop science
Genetics rarely explains something as visible as hair texture with just one gene. EDAR comes close. A single change in this one gene tracks closely enough with hair-shaft thickness that researchers can point to three distinct profiles from that single spot in the genome — and for a lot of people with East Asian ancestry, that's the same gene behind the thicker, straighter hair pattern seen on average in the population.
This is for fun and for learning, not medical or cosmetic advice. Nothing here is a claim about any individual person's hair, and it changes nothing about what products work for anyone. Keep reading for what the actual research says.
The gene behind the shampoo-aisle claim
The gene is called EDAR, identified in a 2008 genetic scan for the determinants of human hair morphology (Fujimoto et al., Human Molecular Genetics, PMID 18065779). At the specific position researchers studied, one genotype is linked to the typical, ancestral hair-thickness profile, a middle genotype has an intermediate effect on hair shaft thickness, and a third genotype is associated with noticeably thicker hair shafts.
One variant, three traits
What makes EDAR a favorite example in genetics courses isn't just the hair effect — it's that the same genotype linked to thicker hair shafts is, in the same research, also linked to two other traits that have nothing obviously to do with hair. One is a distinctive tooth shape called shovel-shaped incisors. The other is scalp sweat gland density — more of them, on average, which sits squarely within the biology of skin itself, since sweat glands are a skin structure. Three visibly different traits, one underlying variant.
Why it shows up so often in East Asian populations
The thicker-hair, more-sweat-glands, shovel-incisor genotype is common in East Asian and Indigenous American populations. It's considered one of the most well-documented examples of recent positive selection in the entire human genome — meaning this particular version of the gene spread and became common unusually fast in human evolutionary terms, likely because it offered some advantage to the people who carried it. What exactly that advantage was is still discussed among researchers, but the signal that something favored it is about as clear as this kind of evidence gets.
So is the shampoo-aisle claim actually true?
For a real, published, population-level pattern — yes, there's a real gene behind it, studied since 2008, with effects that reach well beyond hair. What it isn't is a rule about any one person, or a reason any given bottle of shampoo works or doesn't. Hair thickness has more than one gene contributing to it; EDAR is simply the specific, well-documented piece of the story that happens to also explain your teeth and your sweat glands. The full genotype-by-genotype breakdown is on the EDAR variant page.
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One Gene, Three Hair Types: Meet EDAR. MyGeneLog™. https://www.mygenelog.com/updates/is-there-really-a-thick-hair-gene
Frequently asked questions
What is EDAR?
EDAR is a gene studied for its role in hair shaft thickness. A specific variant in it, rs3827760, has been linked in published research to thicker hair shafts, more scalp sweat glands, and shovel-shaped incisors — all from the same underlying change.
Does one gene really make hair thicker?
Published research associates one genotype at this position with thicker hair shafts specifically — not hair in general, and not a guarantee for any one person, but a well-documented association at the population level.
What else does this same variant affect?
The same research associates it with more scalp sweat glands and a distinctive tooth shape called shovel-shaped incisors. One variant influencing several unrelated-looking traits at once is exactly what makes EDAR such a well-studied example in human genetics.
Who actually carries this variant?
The genotype linked to thicker hair, more sweat glands, and shovel-shaped incisors is common in East Asian and Indigenous American populations, and is considered one of the most well-documented examples of recent positive selection in the human genome.
Is this the only gene that affects hair thickness?
No — hair thickness is influenced by many genes and isn’t fully explained by any single variant. EDAR is simply one specific, well-studied piece of that picture, identified in a 2008 genetic scan for hair morphology.
