See 80Beats: Let Kids Eat Dirt: Over-Cleanliness Linked to Heart Disease
...parents should develop a healthy medium between letting kids get dangerously sick and raising them in a nearly sterile environment. “In the U.S we have this idea that we need to protect infants and children from microbes and pathogens at all possible costs. But we may be depriving developing immune networks of important environmental input needed to guide their function throughout childhood and into adulthood”
