The study linked above says that exposing kids to peanuts lowers the chance of them developing peanut allergy — and people (including the authors of that articl

The study linked above says that exposing kids to peanuts lowers the chance of them developing peanut allergy — and people (including the authors of that article) tend to make the faulty assumption that this means peanut allergy is caused by not being exposed to peanuts early enough. As you’ve highlighted this would imply that cultures where there are no peanuts would be filled with peanut allergies — but that’s not the case. I suspect that there’s a cross reactivity going on. Infants are exposed to an allergen and their immune system develops a good response for it. That response also applies to peanuts, unnecessarily. Had they been exposed to both peanuts and the true allergen then their immune system would’ve learned to discriminate. A similar example — some US citizens are exposed to poison Ivy. They develop a stronger and stronger response after multiple exposures. Later (as a consequence) they are also allergic to Mango because Mango has some kind of similarity to Poison Ivy, from the immune system’s point of view. The Mango allergy could be reduced if they had been also exposed to mango… but mango isn’t the problem — Poison Ivy is!