I ate nuts throughout both of my pregnancies, and fed my DC peanut butter from a young age. DD is allergic to nuts, DS isn't. Both pregnancies (and young childhood) with same diet, both children now with different dietary requirements. DD gradually grew into her allergies. She became allergic from the age of eight to brazil nuts, in particular, almonds (and associated stoned fruit, like peaches and cherries etc). She was fine with hazelnuts, but then her allergy progressed and now cannot eat them.
Just dispelling the theory that if you eat nuts during pregnancy and feed your young children nuts (or any allergen), doesn't always necessarily mean they will be immune. DD didn't used to be allergic to Penicillin, but now she is. So it's not always the mother's fault, as to what they may have consumed during pregnancy.