@OldBrushNewPaper I think a key question is how many people *first* developed allergies as adults vs. *added* them.
I’ve been allergic to peanuts since I was maybe 2, and started developing allergies to tree nuts and legumes in my late teens/early 20s, but you can look at that as an expansion of the original allergy.
Whether there’s a different mechanism or trigger (other than meat allergy) for cases like that vs. cases like yours where it comes out of nowhere, would probably reveal a lot.