My suspicion is more like allergy theory, wherein if most of your life has no allergens (e.g. no pets, city life) then when you encounter the tiniest of allerge

My suspicion is more like allergy theory, wherein if most of your life has no allergens (e.g. no pets, city life) then when you encounter the tiniest of allergens (a suspicious teenager wearing a hoodie) your system goes on total self paralyzing freakout (anaphylaxis).