Before you slap your child's hand out of his mouth, consider this new study showing that a nail-biting habit could actually save you on doctor bills in the future.

In a New Zealand study of 1,037 children, researchers found that children who had reportedly had been biting their nails or sucking their thumbs at young ages were found to be less reactive to the allergy skin prick test when by the time they were 13. And those results continued to hold true when they were tested again at age 32.