Where do allergies come from? – CNN.com.


Scientists know what causes allergies. When particles of pollen, pet dander or certain types of food enter our bodies, they’re called antigens. If your body has a sensitivity to that particle, it mistakes the harmless element for a dangerous invader, according to the American Academy of Allergy, Asthma and Immunology. The particle then becomes what we call an allergen, although a sensitivity to a substance alone doesn’t guarantee you will develop an allergy.


Allergens cause your body to produce Immunoglobulin E, or IgE, antibodies. Antibodies are used to identify and destroy dangerous invaders. Unfortunately, IgE antibodies also release histamine and other chemicals that can create an allergic reaction.


But what causes one person to become sensitive to these indiscriminate antigens floating through the air, while another sails through life with dry eyes and clear sinuses?


Scientists aren’t exactly sure, but they have a few ideas.