We do know that if one of your parents has allergies, your chances are 30% that you will have allergies too. If both parents have allergies, your risk doubles to 60%. However, genetics does not explain the relatively recent spike in allergies, with industrialized countries leading the pack.

There are two current theories that seem to have some empirical basis: the allergen exposure hypothesis and the hygiene hypothesis.

The allergen exposure theory says that exposure to allergens leads to increased sensitivity. Our exposure to chemicals of all kinds, including preservatives and artificial ingredients in our food, leads to sensitization. We are also more likely to keep pets indoors, which is a luxury that previous generations did not indulge in. These conditions are concentrated in urban areas where people are living in a sea of pollution in the air, synthetic materials and household chemicals. This theory is definitely supported by the data that shows that there is a real prevalence of allergies in developed countries and urban areas.

Another theory says that we keep our environments too clean. This means that your immune system isn’t being challenged by viral, bacterial, fungal or parasitic organisms. As a result, the immune system begins to malfunction by attacking harmless environmental substances. Interestingly enough, research shows that people who have had measles have fewer allergies. In fact, children who have had early infections (especially without antibiotic treatment) have fewer allergies too.