Soutra all of what you say is of course true, and it is not so much a case of'teaching' (I probably should not have used the word 'learn') but of giving our bodies the chance to cope with some of the bacteria and infections which are out there. If we are constantly cleaning, scrubbing, disinfecting, then the immune system gets used to that. Having said that, I agree we do live in a wider world and diseases and infections are more easily spread. There are however, hundreds (probably thousands) of my generation alive today, all of whom lived without the benefit of anti-biotics,but possibly on the other hand would not be alive if it were not for the advances made in medicine. We have to live for the day is the anwer I suppose.