Allergies are weird and our understanding of them is very incomplete. My son has/had a peanut allergy (very successful oral immunotherapy, knock on wood) and I ended up doing a lot of research. One study that is particular interesting is this one: https://pubmed.ncbi.nlm.nih.gov/26728850/
It shows that east asian children, who very rarely have nut allergies in their home countries, develop nut allergies at a higher rate than non-asian children when born in Australia while east asian children who immigrate to Australia after their early infancy continue to maintain very low rates of nut allergies.
It shows that east asian children, who very rarely have nut allergies in their home countries, develop nut allergies at a higher rate than non-asian children when born in Australia while east asian children who immigrate to Australia after their early infancy continue to maintain very low rates of nut allergies.