I have a theory about the nut thing. Purely a theory mind....
Nuts are always labelled reminding us that young children can choke on nuts. Grapes and apples (for example) are also a ckoking hazard for young children, but they are not labelled so.
My theory is that in the past, children have had coughing/choking type allergic reactions to nuts, but they have not been recognised as such at the time and hence the warnings about choking hazard.
There are 5 sibs in our family, brought up in the 70s, all of us are allergic types, you know hayfever, asthma, animals etc, but interestingly enough, none of us had food allergies. Between us, so far we have 8 children. 4 are hayfeverish etc and three have/had (now outgrown) food allergies. It is too soon to tell with the youngest one.
I had an allergy appointment for ds the other week and I asked the consultant whether I should avoid nuts during this pg, and his answer was that we don't know.