I have a tree allergy but hickory nuts don’t seem to bother me. Why?

I have a diagnosed tree nut allergy. I had problems with pecans and walnuts so I saw a doctor about it. I consider it mild because I do not have to avoid the warnings on foods “may have been processed in machines that also processed tree nuts”

I am able to eat peanuts, in fact I eat them quite frequently in foods and also raw. I love them!

Now, about the hickory nuts. My mother and uncle are always raving about how good they are to eat. They sit around and eat them as snacks quite frequently. I’ve actually been spending many hours a week picking up hickory nuts before I can mow the lawn, and often help un-husking them so they can sit around and dry.

Out of curiosity, yesterday, I ate a few of them to see if I was going to be allergic to them. It seems that I am most certainly NOT allergic to them.

How can this be? Is the ‘tree nut’ allergy a broad term meaning that a person can be allergic to one/some or all tree nut varieties?

I am very curious and couldn’t find this information online when searching around. Does anybody have any insight on it? I would love to be able to tell my Grandmother that she can start putting nuts in her breads and treats again.. as long as they’re hickory nuts.