It's also pretty unusual to be allergic to all forms of nuts (my son has allergies so I have talked about it a fair amount with doctors) and it seems like a big coincidence for both of them to have the same allergies.

There are lots of food intolerances other than Anaphylaxis-allergies, though, and people often refer to them as allergies because it is the only way to get other people to take them seriously.

Mast Cell Activation Syndrome is one

and also nuts can be major migraine triggers.