Is it a myth that the bodies resistance to germs be "built up" by exposure? I'm not sure is this is more a medical question, but I'm thinking it's more of something biologists would address? When I see people criticized about eating things that have come into contact with unclean or doing other things that expose them to germs. I'll often hear people who know something about the immune system respond that they believe it's a good thing and it will build up or strengthen there immunity to be exposed to lots of germs. Its always sounded to me like a conclusion that they've reached on there own and weren't taught in school or such and It's not sounding very scientific. I've suspected for a while that this is just a myth... It seems to me it shouldn't really matter the quantity of germs you are exposed to as much as the variety. Being exposed to a variety would be a bad thing and immunity is irrelevant, as it seems to me, since if you happen to be exposed to the wrong germ it could be very harmful?