it's not that good hygiene is bad for us, it's that all these lysol etc are bad for us. i ate dirt as a kid and now the only thing i get sick from is sinus infections and maybe a cold once every couple years. kids raised in immaculate houses haven't built their own immune systems up. but these are not likely to result in germ cell changes, only somatic. but it could still kill a great number of us.
but. we are still very selective about those we mate with. we just have new criteria now. for instance, obesity is killing America off, and it just so happens that we're (as a society) attracted to really skinny people. coincidence? i think not.
i don't have kids, but i'm a swim instructor. i work with kids in the elements. last year walking pneumonia was going around. got it. but that's about all.
it's more likely the stress in your life than the exposure. although exposure to virus does determine the load and the severity of infection.