I think that the immune system "correlates" them with other harmful substances which are sometimes but not always present. The number of possible culprits is lo

I think that the immune system "correlates" them with other harmful substances which are sometimes but not always present. The number of possible culprits is long: pesticides, random cleaning products used on the processing equipment, sometimes mold can grow on peanuts if they're stored improperly, the list goes on. Our immune systems are in many ways similar to police forces, and if they hear "a problem being reported" often enough while peanuts are around, they may just bunch them together with the offender. The problem is compounded by a dirty baseline environment. In the early stages, the immune system is "primed" with a "baseline" of what should and shouldn't be there, but if the VOCs and such are already there, it just learns that they are OK and doesn't react to them.