Q: I keep my house extremely clean to protect my one-year-old child from germs. Is keeping everything very clean good for his health?

A: Thomas McDade, associate professor of anthropology at Northwestern University, Illinois, USA, has completed a study on the link between exposure to germs in infancy and inflammation in young adulthood.

He says: "Most of the germs in our homes are harmless. These may help prevent kids from developing allergies and asthma, as well as other diseases. The trick is to reap the benefits of exposing our kids to harmless germs, avoiding pathogens."