Causes of Allergy

The risk of an allergic reaction is dependent on either host or environmental factors. An allergy is dependent on its host when the person is genetically predisposed for that allergy, either through inherited disease or congenital deficiency. An environmentally-dependent allergy is triggered when the person comes in contact with an infectious disease, an airborne allergen, pollution, or if they change their diet.

Genetic Causes

A parent with an allergy is more likely to pass it to their child, and the child's allergy is also likely to be more severe. Identical twins will share the same allergy 70% of the time.

Environmental Causes

A person is more likely to suffer from an allergy if they live in a highly industrialized country, such as factory-heavy regions. On the national level, allergies are more common in an individual that lives in an urban area as opposed to a rural area.