Learn about the causes of allergic reactions in some people

Everything from hay fever to a peanut allergy can make life tragic for those who suffer from it, but the reason we get it isn't quite as simple as it seems at first.

Allergies are caused by an overactive immune system. There is evidence that this is inherited, but several studies have also shown that growing in an excessively clean environment can lead to allergies. People from large families tend to be exposed to more bacteria and have a lower chance of developing allergies.

If you had a skin cream containing peanut oil as a child, you are more likely to have a peanut allergy as an adult, and soybeans in formula milk may also trigger a peanut allergy, possibly because the proteins have similar molecular shapes.