Wet or Dry Earwax? It Is in Your DNA

You have probably never thought of your earwax as a genetic readout, yet it is one of the tidiest examples in all of human biology of a single letter of DNA shaping a visible trait.

Two kinds of earwax

Human earwax comes in two broad types. Wet earwax is sticky, moist, and yellow-brown. Dry earwax is flaky, pale, and crumbly. Almost everyone falls cleanly into one camp or the other, and which camp you are in is settled largely by a single position in your genome. There is little in between, which is unusual for a human trait and part of what makes this one so interesting.

The ABCC11 switch

The gene responsible is ABCC11, and a single variant within it, rs17822931, does most of the deciding. The change swaps one amino acid for another - written as Gly180Arg - and at the DNA level it is described as 538G>A, a G becoming an A at that spot.

• The G allele produces wet, sticky earwax.
• Two copies of the A allele, the AA genotype, produce dry, flaky earwax.

Because you need two A copies to get the dry type, the wet version behaves roughly like the dominant one. A single G is usually enough to tip you into the wet camp. This is about as close as a real human trait gets to the simple textbook picture, though even here it is better read as a strong tendency than an absolute rule.

One variant, several linked effects

What makes rs17822931 so satisfying is that the same variant does more than one job. ABCC11 codes for a transport protein that is active in apocrine glands, which sit in the armpits as well as lining the ear canal. So the version that gives you wet earwax also tends to come with typical apocrine underarm odor, while the dry-earwax AA genotype is associated with noticeably reduced underarm odor.

That is a lot of downstream biology riding on one letter. Earwax texture and body odor travel together because they share the same molecular pump. It is a clean illustration of how one variant can ripple out into several apparently unrelated traits - a phenomenon worth remembering the next time a result seems to explain “one thing.”

A trait with a geographic pattern

The dry, A version is common in East Asian populations and comparatively less frequent elsewhere, where the wet type predominates. Patterns like this are why allele frequencies vary so much from group to group, and why a variant that is rare in one population can be the norm in another. It says nothing about any individual - it is simply a reflection of population history.

Finding it in your own file

If your raw DNA export includes this position, you can look it up directly. Searching for the rsID will show your genotype at that spot:

rs17822931	16	48258198	GG

Two Gs point to wet earwax, an A and a G still lean wet, and two As point to the dry type. If you are new to reading these lines, our guide to the anatomy of a raw DNA file walks through each column, and what SNPs are covers the basics of single-letter variants like this one.

A small piece of a bigger picture

Even a trait this cleanly linked to one variant is best framed as an association, not a certainty. Genotype nudges the odds; it does not hand down a verdict. The value in a result like this is not prediction so much as insight into how your genome works - one switch quietly steering more than you would guess.

You can explore variants like rs17822931 privately with on-device DNA analysis that keeps your raw file in your browser and never uploads it.

This article is educational and is not medical advice.