Parents might want to think twice before halting childhood habits like nail biting and thumb sucking.
A McMaster University researcher has found an upside to what are commonly considered bad behaviours.
One thousand children in New Zealand between the ages of five and eleven were studied based on these habits.
Atopic sensitization was then measured by skin-prick testing at age thirteen.
The study found that children that were found to bite their nails and suck their thumb were less likely to be allergic to house dust mites, grass, cats, dogs and airborne fungi.
It appears, according to researchers, that early exposure to dirt or germs, reduced the risk of developing certain allergies.
However, the study did not find associations between the oral habits and development of asthma or hay fever.