[salty_biscuits]

It would be a reference to the hygiene hypothesis, that being too "clean" leads to lack of exposure to things we evolved to encounter in the environment (worms mostly) which causes the immune system to go a bit wrong, causing allergies and autoimmune conditions.

[ineedasername]

Ah, okay. I've heard that before but thought it was basically fringe science. My assumption has simply been that allergies always existed like this, but those with more severe ones died off very young and the concept of "allergy" somewhat non existent. I'll admit the possibility though, ever if I'm very reluctant to lump it together with more obvious wealth-associatated issues.