Sanitizing and sterilizing your little one’s environment is just one of any parent’s most natural instincts. We don’t want our precious little angels exposed to dirt and bacteria, especially when they’re babies. Who among us hasn’t instantly washed off a pacifier that fell on the floor? 

Jack Gilbert, a father of two who studies microbial ecosystems at the University of Chicago, decided to get to the bottom of how exposure to dirt and bacteria affects our kids. He says we should feel free to let them play in the mud and enjoy friendly licks from the family dog without worrying about germs.

“It’s fine to wash their hands if there’s a cold or flu virus going around, but if they’re interacting with a dog and the dog licks their face, that’s not a bad thing,” he says. “In fact, that could be extremely beneficial for the child’s health.” 

Exposing kids to dirt is good for them; it helps build their immune system. In fact, Gilbert agrees that allergies are the result of parents trying to protect their kids too much. We don’t eat as many fermented foods as humans have in years past, and we over-sterilize our surfaces.

This causes our kids’ immune systems to become hyper-sensitized, which can trigger inflammatory reactions like asthma, eczema, and food allergies.

And licking your child’s dirty pacifier rather than washing it off really is beneficial to their health. Citing a study of over 300,000 children, parents of the “pacifier licker” variety have kids who “developed less allergies, less asthma, less eczema,” Gilbert says.

So when you get A Look from one of your friends or relatives the next time they see you doing this, you can cite actual scientific research as a defense. Now go on and let your kids experience the world. Let them get their hands dirty. Science says they’ll be A-Okay.