Habits can be hard to break, but a new study has good news for anyone who was a thumb sucker or nail nibbler as a child. Researchers from New Zealand's University of Otagao have found that those who were prone to sticking their fingers in their mouths as a child are less likely to develop allergic sensitivities to things like dust mites, grass, pets and airborne fungi as an adult.
The study, published in the journal Pediatrics, measured the habits of more than 1,000 children born in 1972-73 and tested them at the ages of 13 and 32 for any allergic reactions. They found that at 13 years old, only 38 per cent of children who were prone either sucking their thumb or biting their nails showed symptoms of allergies in a skin prick test, compared to 49 per cent of those who resisted the urge to insert their fingers in to their mouths. This dropped to 31 per cent if they both sucked their thumb and bit their nails, and they continued to show such associations when they were tested at 32 years old.
"The findings support the 'hygiene hypothesis', which suggests that being exposed to microbes as a child reduces your risk of developing allergies," says lead author of the study Professor Bob Hancox.
But if you do see your child’s fingers move menacingly towards their face, the researchers still advise against encouraging these bad habits as Stephanie Lynch, a medical student who undertook the study, explains: "Although thumb-suckers and nail-biters had fewer allergies on skin testing, we found no difference in their risk for developing allergic diseases such as asthma or hay fever".