When the immune system overreacts to a usually safe food, it is called an allergic reaction. The most severe reaction is called anaphylaxis. Anaphylaxis (a sudden drop in blood pressure) can sometimes, but rarely be fatal (killing about 1 of 2.5 million). Otherwise, common symptoms of food allergy are things such as hives, eczema, asthma and gastrointestinal symptoms (i.e. vomiting, diarrhea, abdominal cramping).

Why do some people get food allergies? Could it be a result from genetics? Because previous twin studies have shown that there does seem to be a high rate of heritability of allergic diseases, a British study was conducted to compare the incidence of peanut allergy among siblings with general population incidence. The study involved 58 sets of twins, 14 of which were identical, and 44 of which were fraternal. These twins were recruited for having at least one member of the pair having a peanut allergy. 70 of the 115 had a history of peanut allergy.

64% of the identical twins both had allergic reactions to peanuts, which was followed by a mere 7% between the fraternal twins. The conclusion was that based on the data and a model considering environmental and genetic factors, researchers calculated a heritability rate of 82%-87% for peanut allergy. The problem with this conclusion? Though the British study showed a genetic component in peanut allergies, environmental factors may have biased the results.

When they did not consider genetic factors, the rate dropped to just under 19%.

A group of researchers in the July 2000 Journal of Allergy and Clinical Immunology, the peer-reviewed, scientific journal of the American Academy of Allergy, Asthma and Immunology (AAAAI) agree that Genetics play a significant role in peanut allergies.

Lead researcher Scott Sicherer, M.D. along with some of his colleagues from Virginia and Belgium performed a twin study. Their intent was to see if genetic factors influenced peanut allergy. They were checking this by comparing the incidence of peanut allergy between the identical twins and the fraternal twins. Twin studies are used frequently to provide information on how environmental and genetic factors should be compared and treated.

Because there has yet to be solid evidence that there is a direct link between hereditary and allergies, many agree there needs to be more research and more studies dedicated to examine the role between genetics and allergies, so that we may reach a conclusion to this question.