Science says either the parents are lying or the little brats are faking it:
Researchers from the University of Portsmouth (U.K.) have discovered the reason why food allergies have increased in recent years: hypochondria. It turns out that four out of five kids who believes he or she is allergic to a food, isn’t. The researchers surveyed over 1,500 children, along with their parents, about food allergies and intolerances. Then they tested those who reported problems, both with skin fold tests and by feeding them the offending food. The results were completely unexpected....This doesn't surprise me in the slightest. I've noticed that most children whose parents say they have food allergies are obnoxious, spoiled little brats who whine about everything and are allergic to the notion that they are not the center of the universe
About 12% of children claimed to have adverse reactions to a food, with peanuts, dairy products, wheat, and fish the most common. Only 2.3% actually had a problem, some with merely an “intolerance,” and some with an actual allergy.