Societies develop rules of etiquette for a number of reasons: To signal that you come in peace (in the case of handshakes), to embarrass you at the dinner table (the justification for dessert spoons and fish forks) or to keep those around you safe from whatever leaves your mouth when you sneeze (the case for covering your mouth when you need to achoo). The taboo against picking your nose exists because it looks nasty, and more importantly, it can damage your nostrils and spread disease.
Joseph Han, the medical director of the division of rhinology, endoscopic sinus and skull base surgery at the Eastern Virginia Medical School, supports the ban on nose picking. Beyond being a nasty habit that can cause nosebleeds, he says, “For some, it can cause septal ulcerations and crusting.” But mainly, he adds, it makes it super easy for whatever germs might be on your fingers to enter your body through the sensitive membranes that line the inside of your nostrils.
However, on the other finger, er, hand, there’s Scott Napper, a biochemistry professor at the University of Saskatchewan.
He believes that preschoolers have it exactly right: Nose-picking and—brace yourselves—booger-eating might actually be good for you. He hypothesises that by eating their boogers, kids might gain exposure to certain pathogens and ultimately boost their immune systems.
But you aren’t a preschooler, and unless you want to be known as the local Ralph Wiggum, it’s best to follow conventions and keep your fingers out of your nose.