Good news: The fact that your kiddo sucks their thumb or bites their nails might not be a total fail. Turns out thumb sucking and nail biting could actually help protect kids from allergies, according to a new study published in the journal Pediatrics.

It all hinges on something called the "hygiene hypothesis," which is the idea that we're making our kids' environments so clean that their immune systems don't get a chance to develop effectively. So, by exposing babies to germs, it gives their little immune systems time to develop and strengthen. Put down the Lysol and help your baby's health. Sounds like a sweet deal.

"The problem with extremely clean environments is that they fail to provide the necessary exposure to germs required to 'educate' the immune system so it can learn to launch its defense responses to infectious organisms," according to the Food and Drug Administration. "Instead, its defense responses end up being so inadequate that they actually contribute to the development of asthma."

And the rate of allergies is unquestionably on the rise. According to the American Academy of Allergy Asthma & Immunology, allergy rates have continually risen across industrialized countries for over 50 years and "Worldwide, sensitization rates to one or more common allergens among school children are currently approaching 40-50 percent."

Now, doctors are saying that kids putting germs in their mouths through everyday thumb sucking and nail biting could give their immune systems the workouts they need to get strong and stay healthy.

The study looked at 1,037 kids born between 1972-1973 and followed them for more than 30 years. They were tested at age 13 and 32 for allergen sensitivities.

"At age 13, 30 percent of the children who bit their nails or sucked their thumbs showed sensitivity to allergens such as dust mites, grasses, and dog dander, compared to 49 percent of the children who displayed neither habit," according to Today. "Just 31 percent of children with both habits showed sensitivity."

While parents shouldn't encourage either habit, perhaps they can feel a bit better about letting the occasional thumb in the mouth slide at bedtime or during bouts of anxiety.

But there are reasons to encourage kids to keep their hands away from their mouths. Thumb sucking, once a kid's permanent teeth start to come in, can cause dental problems, according to the American Dental Association.

"After permanent teeth come in, sucking may cause problems with the proper growth of the mouth and alignment of teeth," The ADA said. "It can also cause changes in the roof of the mouth."

Nail biting, according to National Public Radio, can become problematic if it becomes a pathological behavior and can even rise to the level of an Obsessive Compulsive Disorder if it can't be controlled.

So the good news for parents is that maybe nail biting and thumb sucking aren't as problematic as we once believed, but they're still worth keeping an eye on so the behaviors don't grow out of control and actually do harm.