Are you wasting money on deodorant? The answer can be found in your ears

If a newspaper headline asks "have scientists found the gene for x?", chances are the article underneath could be replaced with the word "no". But a single gene variation possessed by about 2% of people in the UK means they don't produce the secretions in their underarms that attract smelly bacteria. Research from colleagues of mine in Bristol suggests that despite this, most of these sweet-smelling people still use deodorant even though they don't need to, wasting money and potentially exposing themselves to unnecessary chemicals.

Very few human traits are truly "Mendelian"; that is, coded for in our DNA by a single gene (so named after Gregor Mendel, the 19th century green-fingered monk whose pea experiments paved the way for genetic understanding). There are a few diseases that are caused by single gene mutations, such as cystic fibrosis and Huntington's, but the transmission of inherited traits is for the most part a lot more complicated than differences in single genes.

There is one trait known to be dictated by a single gene though: earwax type. Most Europeans have wet earwax, because they have at least one copy of the "wet" version of a gene (catchily called ABCC11). Just over a million people in the UK have a rarer dry type of earwax, as they have two copies of a different version of the gene (we all have two of every gene, one from our mothers, and one from our fathers).
This gene doesn't just define our earwax type. It also holds the code for building the protein that transports sweat out of pores in our armpits, where it attracts the bacteria that cause body odour. Or at least, one version of it does. The lucky "dry earwax" people don't produce the protein, so they don't make the apocrine underarm sweat that attracts bacteria (it's worth noting we produce two types of sweat, the other being body-wide ecrine sweat, salty water, which isn't affected by this gene).

Ian Day and Santi Rodriguez, two authors of the new study, wanted to find out whether people who didn't sweat still used deodorant. In their sample of 6,495 women (some of the mothers from the Children of the 90s birth cohort), they were surprised to see that more than three-quarters of those with the rare non-smelly genotype still wore deodorant.

The researchers are based down the corridor from me (full disclosure: we are part of the same MRC Centre, but don't work directly together), so I asked them why they thought this might be. Day pointed out that even if you yourself don't produce sweat, it's likely that your parents will have one copy of each version of the gene, meaning they will. Deodorant use is probably encouraged by parents during childhood, so it could become a habit before a child notices they don't smell.

Interestingly, the relative levels of the different gene versions differ by population. In east Asia the pattern is reversed, and most people don't produce smelly sweat. A quick trip to a supermarket in Japan will show you the cultural differences in popularity of deodorant usage; a single shelf over there, versus aisles of choice here in the UK. Not only that, but the minority who do have smelly sweat will sometimes resort to surgery to stop it, such is the stigma in these predominantly non-smelly populations.

But does it matter? So what if people use deodorant without needing it? Usually deodorants have fragrance in them, so even if you don't smell of sweat, why not smell of Lynx? Well, a quick look at the ingredients in Lynx Dry (or, if you're not a teenage boy, the list is similar for Nivea and most other deodorants) shows butane, propane, aluminium derivatives and alcohol, as well as the parfum which produces the distinctive aroma.

Alcohol can cause skin irritation in some people, as can the aluminium derivatives, which block the pores. Even if you don't suffer allergic reactions or irritation, avoiding putting these on your skin is unlikely to be a bad idea. And that's before the cost has been considered. The authors calculate that £9m per year is wasted in the UK by people buying deodorant they don't need. For an individual, over a lifetime of use, this amounts to thousands of pounds.

So is it worth having your genes checked to see if you need to use deodorant or not, or risk social exclusion by not wearing any for a week and seeing if your colleagues start waiting for the next lift? Luckily, it's even easier to find out – a quick look in your ears to check your earwax type will tell you whether you've been spraying your money away unnecessarily!