Slight argument taking place here. So lets see your take on it.
My wife claims that keeping kids away from germs is really, really important and that the stuff about exposure to germs making them strong is a myth.
Me, being a bloke, reckon that the more exposure to every day dirt, germs and general dirtiness is just fine and improves their immunity system. I'm not suggesting they be allowed to wallow in shit but they stuff stuff in their faces every day that they pick up off the floor and while it might produce a slight issue from time to time, it ultimately improves their ability to respond to real nasties.