Thumb-sucking, nail-biting have a positive side: Kids less likely to develop allergies

Children who are thumb-suckers or nail-biters are less likely to develop allergic sensitivities, research has found. And, if they have both ‘bad habits’, they are even less likely to be allergic to such things as house dust mites, grass, cats, dogs, horses or airborne fungi. The finding emerges from the long-running Dunedin Multidisciplinary Study, which has followed the progress of 1,037 participants born in Dunedin, New Zealand in 1972-1973 into adulthood.