Whether it is asthma, food or pollen allergies, type-1 diabetes, lupus, multiple sclerosis, or Crohn's disease, everyone knows someone who suffers from an allergic or autoimmune disorder. And if it appears that the prevalence of these maladies has increased recently, that's because it has--to levels never before seen in human history. These days no fewer than one in five, and likely more, Americans suffer from one of these ailments. We seem newly,...