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What causes allergies in some people?

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Everything from hay fever to peanut allergies can make life a misery for those who suffer from them, but the reason we get them isn’t as simple as it first seems.

Asked by: Jake Mellor, Manchester


Allergies are caused by an overactive immune system. There’s evidence that this is inherited, but many studies have also shown that growing up in an excessively clean environment can trigger allergies. People from big families tend to have been exposed to more bacteria and have a lower chance of developing allergies.

If you had skin cream containing peanut oil as a baby, you are more likely to be allergic to peanuts as an adult, and soy in formula milk may also trigger peanut allergies, perhaps because the proteins have similar molecular shapes.


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luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.


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