God Made Dirt and Dirt Don't Hurt

Researchers have found that children exposed to farm life at a young age are at less risk of developing some autoimmune disorders, including Crohn's disease and ulcerative colitis. This lends credence to "the hygiene hypothesis". The idea here is that children who grow up on farms pick up more bugs from farm animals, which help their immune systems to develop properly. While it's easy to jump from this and argue that we're too clean, living in a hygienic society has its benefits too: for example, it's nice not to have to worry about the latest cholera outbreak in your town.