There are obvious reasons why somebody may respond badly to the smell of cooking pork—ether ideological (they’re vegetarian or vegan), or religious (Jews and Muslims both prohibit the consumption of pork, while Buddhists and Jains are strict vegetarians). But two different studies suggest that a negative reaction to the smell of bacon may be happening at a deeper, subconscious level. And for other signs something’s off with your sense of smell, If You Can Smell This, You’re Drinking Too Much Caffeine, Study Finds. A 2019 study from the Monell Chemical Sense Center, an independent nonprofit basic research institute based in Philadelphia, showed that small changes in a single olfactory receptor gene can greatly impact how strong and pleasant a person finds an odor. These receptors in the nose encode information about what a smell is before the information reaches the brain, and humans have around 400 different types of receptors. One molecule of odor can activate several receptors, while a single receptor can be activated by several different odors. And for more smells you may not be able to detect, check out why You May Be Immune to This Awful Odor, New Study Saysae0fcc31ae342fd3a1346ebb1f342fcb In many cases, these receptors are super useful—they tell you immediately if a smell is toasting bread or a burning kitchen, for example. But the Monell Chemical Sense Center researchers found that just a single receptor being changed was enough to change a person’s odor perception. “Because most odors activate several receptors, many scientists thought that losing one receptor wouldn’t make a difference in how we perceive that odor,” senior researcher Joel Mainland, PhD, an olfactory neurobiologist, said in a statement. “Instead, our work shows that is not the case and changes to a single receptor can make a big difference in how you perceive an odor.” And if you’re worried about the odor coming from your own body, you’ll want to know What’s Making You Smell Bad, According to Science. A 2012 study out of Duke University Medical Center found that 70 percent of people have two functional copies of a gene linked to an odor receptor that can detect androstenone, a compound common in male mammals and present in pork. People with one or no functional copies of the gene can tolerate the scent of androstenone much more easily. “The results showed that people with two copies of the functional variant of the gene for that odor receptor thought that the meat smelled worse with higher levels of androstenone added,” lead researcher Hiroaki Matsunami, PhD, a Duke associate professor of molecular genetics and microbiology, said in a statement. So next time someone balks at the scent of your breakfast bacon, don’t just blame them for being a fussy eater—it may well be their genes talking. And for more on scents and our current health situation, know that If You Can’t Smell These 2 Things, You May Have COVID.