Hi everyone.
I am trying to understand "allergies" and this is where I get hung up:
I understand that a so-called "allergy" is no more than a trigger. We have an experience and the body connects this experience with an "allergen" that is around at the time. After that moment the "allergen" will trigger a symptom. The body reacts by taking action that might make sense in regard to the experience we made the first time it remembered the "allergen".

Would you agree that the above is a correct description for an "allergy"?

And if so, why are there certain "allergens" that more people react to? Like, let's say peanuts? Why do more people have reactions and severe reactions when consuming peanuts? But why don't we have as many people who have the same reactions to bananas or lettuce? I never heard of anyone having a severe reaction to a lettuce leaf.

But if the above description of an allergy is correct, there should not be any difference between lettuce and peanut.
What is it I am not understanding? What am I overlooking?

If we take the example of dairy products, it is clear. Mammals are designed to drink milk until they eat solid foods. For about three years. After, nature does not believe a mammal needs the enzyme anymore to break down milk. Milk is for babies; each species has its own type of milk for its needs.

Wheat is highly altered to serve as a high-caloric food to serve to feed the masses. The same is true for corn, which already was manipulated.

I understand, that plants that were changed drastically can cause problems. But I don't understand why some "things" cause more "allergies", or trigger more, than others. Why is that? Does anyone understand this better than me?