Hair Density

Your result, the one DNA position behind it, and what the research says.

5/10 confidence.

About Hair Density

How many hairs grow per square centimeter of scalp varies several-fold between people and between populations, quite separately from whether hair is thick or thin per strand. NRP2 is a receptor for the secreted semaphorins that steer growing nerve fibers, and it also has a part in forming small lymphatic vessels. Whether it does anything in a hair follicle is not established. A study of hair density in East Asian populations found this position attached to the count.

Good to know: Density is how many hairs there are; thickness is how wide each one is. Different genes. The source study was in East Asian participants, where hair density differs from European averages. Hair density falls gradually with age in everyone.

Fun fact: A typical human scalp carries somewhere around a hundred thousand hairs, and the number is largely fixed before birth.

Discovery: Hair density was mapped in East Asian populations in 2025.

The Variant

The single variant behind this trait

Gene: NRP2

Variant (rsID): rs3771033

Location: Chr 2:205,731,086

dbSNP rs3771033

The studies

Genetic and environmental factors affecting hair density in East Asian populations (Qian Q et al., The British journal of dermatology, 2025)

Other lifestyle traits

Blond Hair: The pigment switch beside KITLG, the single best-known genetic driver of naturally blond hair in people of European descent.

Eye Color: The biggest genetic switch for blue against brown eyes, read together with two changes that decide the shade it lands on.

Hair Curl: A variant near the trichohyalin gene, which shapes the hair follicle root and is the main driver of straight versus wavy hair in people of European descent.

Back to All Traits

Content updated September 2026.

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