The Body Odour Gene (rs17822931): Scent, Earwax & Matching

Roughly two billion people do not produce underarm body odour. If you mention this in the West, people assume you are joking. We treat body odour as a universal human condition, something to be scrubbed and sprayed into submission. But for most of East Asia, the scrubbing is unnecessary. There is nothing there.

Why? A single nucleotide: rs17822931, a SNP in the ABCC11 gene. One version of this gene pumps odorant precursors into your apocrine sweat. Skin bacteria eat those precursors and excrete the molecules we recognise as body odour. The other version (a Gly180Arg substitution) breaks the pump. No precursors, no bacterial feast, no smell. The same broken pump also produces dry, flaky earwax instead of the wet, sticky kind.

This matters well beyond personal hygiene. If humans evaluate mate compatibility partly through body scent — as the foundational research in genetic matchmaking suggests — then half the world's population is missing the signal. That is a confound worth examining.

The ABCC11 Gene and rs17822931

The ABCC11 gene acts as a pump in your apocrine sweat glands — the glands clustered in your armpits, groin, and around the nipples. These are not the glands that cool you when you exercise (those are eccrine glands, producing mostly salt water). Apocrine glands release a thick, oily fluid that does not actually smell on its own. The smell happens downstream: bacteria on your skin, primarily Corynebacterium and Staphylococcus, eat the secreted precursors and excrete the volatile compounds we recognise as body odour (Natsch & Emter, 2020).

If you have at least one working copy (the G allele, GG or GA), the pump works. If both your copies are the A allele (AA), the pump is broken — minimal or no underarm body odour, and dry, flaky earwax (Yoshiura et al., 2006).

Earwax type and body odour come from the same gene, and that's not a coincidence. Both ceruminous glands and apocrine glands depend on the ABCC11 transporter. Rodriguez et al. (2009) confirmed in Journal of Investigative Dermatology that a functional ABCC11 allele is essential for axillary odour formation.

One gene. One SNP. It determines whether you produce underarm body odour, what type of earwax you have, and how the olfactory channel of MHC-based mate selection works for you.

An Ancient Mutation — Where and When

The smelly G allele is the original, ancestral version. The A allele is a newer loss-of-function mutation that arose ~50,000 years ago, likely in Siberia/Central Asia. It appears in the Ust'-Ishim lineage (~45,000 years ago) and the Tianyuan individual from Northern China (~40,000 years ago).

The geographic distribution today is striking:

• East Asian populations: 80–95% carry AA (no body odour). In Korea and Japan, near 100%.
• European and African populations: 97–100% carry at least one G allele.
• South Asian and Central Asian populations: Intermediate frequencies.

The A allele took over East Asia incredibly fast for a single nucleotide change — speed that usually points to positive selection (Ohashi et al., 2011).

Why We Evolved Body Odour in the First Place

Apocrine glands wake up at puberty, exactly when sexual signaling becomes relevant. They cluster exclusively in reproductive zones (armpits, groin, areolae). They pump out specific chemical precursors rather than generic sweat. Our noses are tuned for this — humans show "particularly high sensitivity" to axillary odours compared to other environmental scents.

Body odour patterns are stable over time, genetically determined, and individually specific. Those are the characteristics of a communication system — one that enables kin recognition, individual identification, and potentially mate-quality assessment.

Why Evolution Then Removed It in Half the World

Three hypotheses compete:

1. Cold climate adaptation (strongest evidence): A-allele frequency correlates with absolute latitude. In freezing temperatures, sweating less saves crucial body heat and moisture.
2. Sexual selection for odourlessness: Natsch & Emter (2020) suggest preference for low-odour partners may have driven the loss-of-function allele to fixation.
3. Population density in agrarian societies: When people went from small nomadic groups to crowded villages, smelling strong stopped being sexy and started being a problem.

These are not mutually exclusive. Cold may have started the spread, sexual selection may have finished the job.

The Sweaty T-Shirt Experiment — Foundational but Contested

In 1995, Claus Wedekind published the famous sweaty t-shirt study. Women preferred the smell of men whose MHC genes were dissimilar to their own (Wedekind et al., 1995). It launched an entire field.

DNA Romance's DRom 1.0 algorithm relies on this premise, using 100 MHC SNPs to calculate HLA dissimilarity. Dissimilar MHC, the theory goes, means you'll find each other's scent attractive. That's "chemistry."

The evidence has become more complicated since 1995:

• Natsch & Emter (2020) found "no evidence for HLA-linked patterns" in odorous compound composition.
• The original sweaty t-shirt results were "not replicated in a larger study".
• Winternitz et al. (2017) meta-analysis found no significant overall effect (Zr = −0.024, p = 0.289).
• Derti & Cenik (2010) titled their PLoS Genetics paper "Absence of Evidence for MHC-Dependent Mate Selection".

The original experiment opened a genuinely interesting line of inquiry. The evidence for a direct MHC-to-odour-to-preference pathway is more mixed than pop-science coverage suggests, and the honest thing is to say so.

The Confound — When There Is No Scent to Evaluate

Layer the ABCC11 finding onto the MHC-odour hypothesis:

• If both partners carry G (both produce odour), the scent-based compatibility test works as advertised.
• If one partner carries AA and the other GG/GA, the channel is one-directional.
• If both partners carry AA, the axillary olfactory channel is dead silent.

This is not a criticism of MHC-based matching. It's a genuine confound: if the mechanism depends on scent, its effectiveness depends on whether scent is actually produced.

But MHC Still Matters — More Than Skin Deep

Smell is not the only channel. ABCC11 controls axillary odour specifically. Saliva, breath, skin lipids, and genital secretions all carry molecular information through ABCC11-independent pathways.

Three lines of evidence suggest MHC compatibility matters beyond any single sensory channel:

1. Wu et al. (2018) studied 262 Asian American speed-daters — a population likely to have a high frequency of the AA allele. Women preferred MHC-dissimilar partners, with effect "comparable to personality" in predicting second-date offers. This was real dating behaviour, not t-shirt sniffing. If MHC-based attraction worked only through axillary odour, this result should not exist.
2. Immune diversity in offspring: MHC-dissimilar parents produce children with broader HLA range and more robust pathogen resistance.
3. Reduced miscarriage risk: Ober et al. (1998) found HLA-similar couples had significantly higher rates of fetal loss.

Kromer et al. (2016) also found associations between MHC compatibility and sexual satisfaction in established couples.

MHC dissimilarity matters whether or not you can smell your partner's armpits. Immune diversity in offspring, reduced miscarriage risk, and chemistry through kissing all operate through channels that have nothing to do with ABCC11.

What This Means at DNA Romance

DNA Romance includes rs17822931 in our analysis. DRom 2.0 already reads this SNP to predict earwax type — the same variant that controls axillary body odour. We know which users carry AA, GA, or GG.

For users with the smelly genotype (GG/GA), the scent-based "chemistry" prediction is backed by research, even if scientists are still arguing over the exact pathway. For users who carry AA, MHC compatibility still predicts immune diversity in offspring and reduced miscarriage risk.

The relationship between MHC genes, body odour, and attraction is more complicated than "dissimilar MHC equals chemistry". We'd rather explain the nuance than pretend it doesn't exist.

Explore your DNA-based compatibility → · Take a free personality test →

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Related reading

• Ten Ways Scent, Sense and DNA Influence Our Relationships
• The Genetic Blueprint of Love: Unraveling Romantic Chemistry
• The Genes For Love