Are twins allergic to the same things?

Understanding allergies, from symptoms to treatment, genetics to environmental factors, and the likelihood of twins sharing allergies.

The more things two people share, the higher their chances of being allergic to the same things. Twins are more likely to share allergies because of everything they have in common, but the story doesn’t end there.

I’m an allergist and immunologist, and part of my job is treating patients who have environmental, food or drug allergies. Allergies are really complex, and a lot of factors play a role in who gets them and who doesn’t.

Your immune system makes defense proteins called antibodies. Their job is to keep watch and attack any invading germs or other dangerous substances that get inside your body before they can make you sick.

An allergy happens when your body mistakes some usually harmless substance for a harmful intruder. These trigger molecules are called allergens.

The antibodies stick like suction cups to the allergens, setting off an immune system reaction. That process leads to common allergy symptoms: sneezing, a runny or stuffy nose, itchy, watery eyes, a cough. These symptoms can be annoying but minor.

Allergies can also cause a life-threatening reaction called anaphylaxis that requires immediate medical attention. For example, if someone ate a food they were allergic to, and then had throat swelling and a rash, that would be considered anaphylaxis.

The traditional treatment for anaphylaxis is a shot of the hormone epinephrine into the leg muscle. Allergy sufferers can also carry an auto-injector to give themselves an emergency shot in case of a life-threatening case of anaphylaxis. An epinephrine nasal spray is now available, too, which also works very quickly.