The number of school-age kids with peanut allergies has doubled in the past decade

Scientists can't quite put their finger on what makes the legume such a threat or why the allergy has become so prevalent. Theories abound, though, and most involve an overactive immune system. "We have done such a good job of eliminating the threats that the immune system is supposed to manage, that it's looking for something to do," says Anne Muñoz-Furlong, CEO of the nonprofit Food Allergy and Anaphylaxis Network. http://www.popsci.com