I would guess that a generous portion is due to the information age. More thing sget reported and since we base our perception of the likelyhood of an event to happen with the frequency of reports, it is easy to skew what we think. Of course, none of that is based on facts, only what we perceive. Not very scientific, eh?
The other half is probably due to a changing environment that has driven the number of cases of infants with allergies up.
Peanut allergies are nothing new and can be fatal in some instances.
Years ago we breat fed kids and they were old enough to stand peanuts when they were weaned.
What we have now is mothers who feed formula and give their kids little tastes of peanut butter when they are just a few months old.
Just a few licks is enough. Why is that? As and aid to food absorption the kids gut is very permeable to the proteins in mothers milk...guess what? Peanut proteins leak through into the blood and the kids system notices it as foreing and raises the antibody alarm and an allergy is caused.
Every kid with a peanut allergy had s stupid mother, aunt or babysitter who fed him peanut butter as a small child. After 1 year old, no problem, the gut has sealed and undigested peoteins cannot penentrate.
Every child rearing course tells you never to feed kids peanut butter, or any other nut butter
I know a 12 year old with a severe peanut allergy who has never been given peanuts because this allergy exists in other members of her family. Both her aunt & uncle have had near misses after becoming seriously ill, one after ingesting peanuts, the other after eating a brazil nut. The 12 year old had a wide spectrum allergy test which showed a marked reaction to peanut.