What you carry at this position in your DNA and what research says about it.
Hair and Facial Features: 8/10 evidence, 24 publications.
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Sample genotype (not yours): A/A
Typical Hair Texture and Thickness
Ancestral genetics at this locus lead to typical hair thickness and texture common in European and African populations. Baseline receptor activity maintains standard hair follicle development.
What this genotype means: Typical hair thickness; Standard tooth shape.
Sample genotype (not yours): A/G
Slightly Thicker Hair and Shovel-Shaped Teeth
Heterozygous genetics at this locus are linked to moderately thicker, straighter hair and unique dental features. This genetic pattern is highly common in people of East Asian or Native American descent.
What this genotype means: Moderately thicker hair; Increased chance of shovel-shaped teeth.
Sample genotype (not yours): G/G
Thicker Straighter Hair and Shovel-Shaped Teeth
Homozygous derived genetics are strongly associated with thick, straight hair and shovel-shaped incisors. This genetic profile is extremely common in East Asian and Native American populations.
What this genotype means: Thicker and straighter hair; High likelihood of shovel-shaped teeth.
Gene function and biological role
Gene Function: The EDAR gene encodes the ectodysplasin A1 receptor, a key protein involved in the development of ectodermal structures [1]. These structures include hair follicles, teeth, sweat glands, and mammary glands [1]. Proper signaling through this receptor is essential for the normal formation of these tissues during embryonic development [1]. Variations in this gene can alter the density, shape, and thickness of hair and teeth [1]. It is one of the most famous examples of recent human evolution and adaptation [2].
Variant Impact: The rs3827760 variant is a missense mutation in the EDAR gene, resulting in a Val370Ala amino acid change [1]. This change enhances the signaling activity of the receptor, leading to distinct physical traits [1]. The derived G allele is highly prevalent in East Asian and Native American populations, where it has undergone strong positive selection [2]. This variant is widely studied as a classic example of human adaptation to environmental pressures [3]. It is also used in genetic ancestry testing to identify East Asian or Native American heritage [4].
Read on the Hair Thickness page
Key Insight: This single genetic change simultaneously influences hair thickness, hair straightness, tooth shape, and sweat gland density.
Location: EDAR. Chromosome 2 · 2q13 · 108.9 Mb
Origin Story: During the last ice age, approximately 18,000 to 28,000 years ago, positive selection favored the derived G allele in East Asian populations. Researchers hypothesize that the mutation increased the branching density of mammary ducts, which may have enhanced the transmission of critical nutrients like vitamin D and fatty acids from mother to infant in low-light northern latitudes.
Estimated prevalence by population
Global 89.5%; European 98.6%; African 97.4%; East Asian 1.3%; South Asian 96.7%; Americas 52.8%; Ashkenazi 96.5%; Finnish 89.6%; Middle Eastern 99.3%; Amish 100.0%.
Estimated AA genotype frequency.
Global 7.0%; European 1.4%; African 2.6%; East Asian 20.3%; South Asian 3.3%; Americas 39.7%; Ashkenazi 3.5%; Finnish 10.1%; Middle Eastern 0.7%; Amish 0.0%.
Estimated AG genotype frequency.
Global 3.5%; European < 0.1%; African < 0.1%; East Asian 78.4%; South Asian < 0.1%; Americas 7.5%; Ashkenazi < 0.1%; Finnish 0.3%; Middle Eastern < 0.1%; Amish 0.0%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Organ Systems
Pigmentation & Appearance
Hair Straightness. Evidence: 8/10. Source: PMID 27487801. Typical Hair.
Hair Thickness. Evidence: 8/10. Source: PMID 18704500. Typical Thickness.
Earlobe Attachment. Evidence: 5/10. Source: PMID 26105758. Attached Earlobes.
Dental & Oral Health
Tooth Shape. Evidence: 3/10. Source: PMID 22648185. Typical Teeth.
Showing effects for A/G genotype
Hair Straightness. Evidence: 8/10. Source: PMID 27487801. Straighter Hair.
Hair Thickness. Evidence: 8/10. Source: PMID 18704500. Thicker Hair.
Earlobe Attachment. Evidence: 5/10. Source: PMID 26105758. Typical Earlobes.
Tooth Shape. Evidence: 3/10. Source: PMID 22648185. Shovel-Shaped Teeth.
Showing effects for G/G genotype
Hair Straightness. Evidence: 8/10. Source: PMID 27487801. Very Straight Hair.
Hair Thickness. Evidence: 8/10. Source: PMID 18704500. Very Thick Hair.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Ancestral genetic profiles at this locus represent the most common state globally outside of East Asia and the Americas [1]. This baseline configuration is associated with typical hair follicle thickness and a natural tendency toward wavy or curly hair [2]. It also correlates with typical tooth shape, lacking the shovel-shaped incisors common in Asian populations [3]. Because this is the ancestral form, it represents the baseline signaling level of the ectodysplasin receptor [4]. Earlobe attachment, facial hair density, and sweat gland distribution are also typical for this baseline [5].
Typical hair thickness; Standard tooth shape.
Sample genotype: AG (Heterozygous)
Inheriting one copy of the derived G allele leads to intermediate physical traits through enhanced receptor signaling [1]. This genetic state is associated with moderately thicker hair fibers and a higher likelihood of straight hair compared to the ancestral genotype [2]. It also increases the probability of having shovel-shaped incisors, a dental trait characterized by scooped-out back surfaces of the front teeth [3]. These physical changes are due to enhanced signaling of the ectodysplasin receptor during development [1]. This variant is highly prevalent in East Asian and Native American populations due to historical positive selection [4].
Moderately thicker hair; Increased chance of shovel-shaped teeth.
Sample genotype: GG (Homozygous)
Two copies of the derived G allele maximize the physical traits associated with this variant [1]. Hair shafts are typically significantly thicker and very straight under this genetic profile [2]. It is also strongly linked to shovel-shaped incisors, which feature a distinct scoop-like shape on the tongue-side of the front teeth [3]. These traits are driven by a highly active ectodysplasin receptor that alters hair follicle and tooth development [1]. This genotype is found in up to ninety-five percent of Han Chinese populations, reflecting intense positive selection during human history [4].
Thicker and straighter hair; High likelihood of shovel-shaped teeth.
Variants with shared genetic architecture
rs1042602 · TYR Gene · Chr 11 · Skin Pigmentation
rs1047891 · CPS1 Gene · Chr 2 · Urea Cycle and Kidney Health
rs10484554 · HLA-C Gene · Chr 6 · Psoriasis Risk
The adaptive variant EDARV370A is associated with straight hair in East Asians.
A haplotype map of the human genome.
A common variation in EDAR is a genetic determinant of shovel-shaped incisors.
A genome-wide association study identifies multiple loci for variation in human ear morphology.
Content updated August 2026.
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