Hygeine Creates Allergies?

I noticed as a child that the people in my classes who had the bad allergies seemed to be the ones with the most cleanliness-obsessed families – it never seemed to make much sense. But now a recent study comparing lab rats with their wild brethren suggests that allergies may well be the result of living in environments that are too clean, to the extent that the immune system can’t cope when presented with what should be a minor annoyance.