Again, anecdote, science of 1... but that can't be universally the case because of me.

I'm Gen X (1979), grew up playing in dirt, house filled with dogs and cats. Ate a fair amount of things, apart from the things I was allergic too: apples mostly. Most of the food I ate was home cooked. My sisters do not have allergies.

It has since gone on to get much, much worse. I can no longer eat carrots or parsnips (which were my favourite). I'm now very allergic to dogs and cats and it wasn't because of a lack of exposure.