I’d been sniffing the hair on my children’s heads – yes, moms do that. And found that they smell very different. I can’t even describe the smell though – one like vanilla soup and the other like citrus tea. That got me wondering what they might smell like as teenagers and then adults. Would my deliciously smelling kids become stinky people with various body odors? Would I need to arm them with deodorants? Was I going to need to do a 3 week research project on finding the best, non-toxic deodorants?
I’ve noticed that men and women and folks of different ethnicities also seem to have different body odors. I’m of Asian descent and have never used deodorant in my life and have probably rarely needed it (although I suppose I should get some second opinions about that). My husband of European descent can have more distinctive scent, but many of my male Asian friends have claimed that showering after the gym is utterly unnecessary from a body odor standpoint.
I got searching. Researching trivial things is a guilty pleasure of mine.
The answer first
Here’s the bottom line on whether you and/or your child will be stinky:
- It’s linked to a gene! A gene called ABCC11 affects how much of a certain protein called MRP8 is secreted in the sweat from your apocrine glands (the sweat glands in your armpits). This MRP8 protein is “responsible for secreting odorous chemicals in a person’s armpit—chemicals which are converted into body odor by bacteria on the skin.”
- A mutated, non-functioning ABCC11 which results in lower secretion of MRP8 has been found in approximately 80-95% of East Asians (Chinese, Korean, Japanese, etc.)
- In the rest of the world, this gene mutation exists in only 0-3% of people of European and African ancestry, and 30-50% of people from South Asia, the Pacific Islands, Central Asia, and indigenous Americans. Those with a mutated ABCC11 aren’t completely immune from body odor, just that they will probably have a lot less of it and maybe indetectably so.
- This gene incidentally also determines the type of earwax you have. A non-functioning ABCC11 gene results in dry ear wax, whereas a normal expression of the ABCC11 gene results in wet ear wax. Therefore, the type of earwax you have (at any age) can help determine your levels of body odor.
What makes the actual body odor?
The main source of our body odor comes from our body’s sweat glands in combination with the bacteria on our skin. At birth we have eccrine sweat glands all over our body which excrete water and salt mostly, but at puberty we develop apocrine sweat glands in the armpit and groin regions. Apocrine sweat glands secrete proteins (including the odor causing MRP8 protein) and lipids and when they mix with the bacteria on your skin, body odor is created.
What’s the connection to ear wax?
The ABCC11 gene that determines your body odor also determines your ear wax type. It’s expressed in humans as two alleles resulting in either sticky brown cerumen also known as “wet ear wax” or dry flaky cerumen aka “dry ear wax.”
The dominant allele, let’s call it “W,” produces wet ear wax and body odor. The recessive allele , say “D” (also referred to as the mutated version of the gene) results in dry ear wax and less of the odor causing protein. If you have two recessive alleles, DD, then you have dry ear wax. If you have wet ear wax then you either have WW or WD. For a refresher on genetic traits and to see how this will be passed down in your family, see here and here.
Check your ears and your child’s ears if you’re curious. For evolutionary reasons still unclear, dry ear wax is found predominately in East Asian populations (as mentioned above).
Why don’t we all smell the same?
Aside from the genetics mentioned above, the bacteria we have on our skin also varies from one person to another and depends on a variety of factors, such as diet, environment, and lifestyle. Mix it with the goods from your apocrine sweat glands and you’ve got your own signature scent!
Things in your diet such as spicy, pungent foods in high quantities can come through your skin. Stress can increase the production of your apocrine sweat glands, and the breathability of your clothes can either trap in your sweat or allow it to evaporate. How often and when you shower (like post-workout) can also determine how much bacteria is on your skin and available to turn sweat into odor.
Bacteria and surroundings nothwithstanding, your scent may also change with age due to a couple major factors. Babies and pre-teens don’t have the apocrine sweat glands that produce the odor-causing proteins. For older people, scientists have discovered that people over the age of 40 emit an odor compound called 2-nonenal that occurs when chemicals breakdown in our bodies as we age. It appears to be linked to the muskier smell that people associate with older people.
So I checked the type of earwax in my kiddos and I’ve got one wet and one dry. Looks like I might have some future Google research on deodorants after all.
The science behind body odor
Factors causing body odor
Why body odor varies
Some people don’t have much body odor.