About 30% of non-breast fed babies are put on soy formula. Peanuts and soy beans are related and this may indeed be behind the increased incidence of severe peanut allergy.
Do you know if there are any studies on the incidence of peanut allergies in vegan families vs. non-vegan? Vegans would exclusively use soy formulas, and they pretty much live on soy anyway, don't they? I see all those soy burgers, soy dogs, soy cheese (yuck and double-yuck!)at the grocery. I'm assuming pregnant vegan women would continue eating it, and that soy (or whatever the allergen in it is) might cross the placental barrier as well.