Let your kids play in the dirt, and with domesticated animals, but wash their hands before dinner

As reported in The Wall Street Journal,

According to the Centers for Disease Control and Prevention, the American immune system is in serious trouble. A study released this year showed a 50% rise from 1997 to 2011 in the incidence of food allergies among children, with a whopping 69% rise in eczema sufferers. The only kids apparently not itching and sneezing were those living on farms and in other insalubrious places.

Found here.