That's pretty young -- before they have really started seriously developing their autoimmiune system -- it probably weakened them and now you do have a legitimiate need to keep them in a clean environment
But most kids don't have that requirement. And if people keep over-cleaning the bugs will just get stronger -- just like the antiboiotic-resistant strains now being found. This problem is bigger than the individuals -- all people will be adversly affected by the mutant anti-germicidal bugs,.
Well...guess my grand kids won't have to worry...their stay at home mother (My dil) cleans the bathroom about once a month (6), lets cats crawl all over the limited kitchen counters and kitchen table....and poop in the clean clothes basket....