Children do a lot of things that adults might consider gross.

However, a new study published in the journal Pediatrics suggests that two so-called "bad" childhood habits, thumb sucking and nail biting, could provide health benefits later in life.

Drawing evidence from an ongoing study of children in New Zealand, researchers found that children who suck their thumbs or bite their nails are less likely to develop allergies as adults.

The New York Times describes the methodology behind the study:

"In the study, parents were asked about their children’s nail-biting and thumb-sucking habits when the children were 5, 7, 9 and 11 years old. Skin testing for allergic sensitization to a range of common allergens including dust mites, grass, cats, dogs, horses and common molds was done when the children were 13 years old, and then later when they were 32. Thirty-one percent of the children were described as 'frequent' nail biters or thumb suckers (or both) at one or more of those ages.

"The study found that children who frequently sucked a thumb or bit their nails were significantly less likely to have positive allergic skin tests both at 13 and again at 32."

Another finding is that two habits are better than one.

According to The Times, children with both habits had an even lower likelihood of testing positive for allergies than those displaying only one habit.

The results seem to lend some weight to the hygiene hypothesis, which posits that "people exposed to potentially harmful bacteria as young children are more likely to grow up able to resist them, whereas those reared in cleaner environments are more likely to suffer from allergic ailments," according to The Guardian.

However, there's still much more to learn. As Robert J. Hancox, an author of the study and an associate professor in the Department of Preventive and Social Medicine at Dunedin School of Medicine, told The Times: "Even if we assume that the protective effect is due to exposure to microbial organisms, we don’t know which organisms are beneficial or how they actually influence immune function in this way."

[h/t The New York Times]