A new study suggests that parents who wash their dishes by hand, rather than in a dishwashing machine, may unwittingly lower the likelihood that their children will develop allergies.

The researchers followed roughly 1,000 young children and their parents living in the Gothenburg area of Sweden. Scientists looked into whether the parents washed their dishes by hand or used a dishwasher then examined whether the children had allergic conditions including asthma, eczema and hay fever.

Ultimately, the researchers found that children raised in households where dishes were always washed by hand had half the rate of allergies. The findings demonstrated only an association, not cause and effect, so it was not clear whether these behaviors directly led to fewer allergies.