My Kid is a Damn Nutter

[Clodfobble]

I'd guess that both are contributing factors. Most allergies are at least partially related to whatever happens to be in your system when your immune system decides to go briefly apeshit. It's why people who move, from anywhere to anywhere, usually find that their seasonal allergies are vastly improved. They're allergic to northern (or whatever) species of trees/pollen, but the people who have lived in Destination City since childhood are allergic to their own trees/pollen. But if the things that happen to be in your system also happen to have crazy-ass non-biological chemical components, like food that's been processed/pesticided/overfed with antibiotics, those food molecules are also more likely to be chosen by an immune system looking for something to attack.