It would be interesting to see an allergy study on kids raised in their own home vs those that grew up in a group childcare setting. Speaking from experience as a parent, those places are like petri dishes for vile diseases. It seems like that would be a much more thorough exposure to disease than playing in the dirt and sucking a thumb.

I live in New York, I often forget to wash my hands when I come home from riding the subway and start hugging my kid one of whose favorite games is "chew on dad". I'm trying to balance out the fear of her catching some exotic imported disease with the hope that her immune system is getting used to handling a variety of invaders.

On the other hand we have less exposure to the bacteria and parasites that live in the dirt and on animals. They trigger (and modulate) a different part of the immune system associated with allergies.

"There can be downsides to thumb sucking, as it can lead to problems from pushing secondary teeth as they come in. But those don’t come in until later, when children are in elementary school. Most children stop sucking their thumb by themselves before they get to elementary school. The American Dental Association recommends that parents start encouraging their children to stop sucking their thumb after age 4 — but even then, they advocate a gentle, positive approach. Many children suck to relieve anxiety, and making them anxious about sucking can backfire! Instead, praise children for not doing it — and help them find other ways of soothing themselves. Putting a Band-Aid on the thumb can help them remember; at night, using a sock or something similar can help with the child who sucks their thumb without realizing it. But again, this is only an issue for older children."

Which ignores that fact that crooked teeth in young children can impact speech development.

Granted, he's always been a determined kid :)

I've lived in Boston and Seattle, no issues. Now I live in Dallas (again) and allergy season is not good. Pretty much a guaranteed sinus infection twice a year.

I think electronics can be coated with an antibacterial film to prevent infections.

Nasal secretions should be good sources of airborne pathogens. Different pathogen profile from fingernails, etc. Wider challenges for a developing immune system.

Yes. They're called "the outside world", and hard as this is to believe, you can sometimes even find your child a spot in one free of charge!

Certain kinds of cigarette vapors make my ears and throat constrict in a matter of seconds.