Asked by: Anthony Wyvill, Harrogate
Possibly because most people now eat far more nuts and peanuts (which are not true nuts but legumes) than they used to. There is a genetic basis to many allergies, but some have to be primed before they have any real effect. One theory is that mothers in developed countries are now eating more nuts and peanuts when they are pregnant. This means their babies are primed for the allergy even before they are born.
Another suggestion is that with concerns over exposure to the Sun, parents are now applying far more moisturising creams and lotions to their babies. These often contain low-grade peanut oil which might then prime the allergy. It might explain the association between eczema and peanut allergy in children, because such lotions are applied to soothe the itching.
However, some research shows that early exposure to peanuts can prevent later allergic reactions. Children in countries where lots of nuts are eaten from infancy do not show the high levels of allergy common in Western countries.