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Are twins allergic to the same things? – Ella, age 7, Philadelphia
Allergies, whether spring sneezes due to pollen or trouble breathing triggered by a certain food, are caused by a combination of someone’s genes and the environment they live in.
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.
What is an allergy?
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.
Y-shaped antibodies are meant to grab onto any harmful germs, but sometimes they make a mistake and grab something that isn’t actually a threat: an allergen.
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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.
A person can be allergic to things outdoors, like grass or tree pollen and bee stings, or indoors, like pets and tiny bugs called dust mites that hang out in carpets and mattresses.
A person can also be allergic to foods. Food allergies affect 4% to 5% of the population. The most common are to cow’s milk, eggs, wheat, soy, peanuts, tree nuts, fish, shellfish and sesame. Sometimes people grow out of allergies, and sometimes they are lifelong.
Who gets allergies?
Each antibody has a specific target, which is why some people may only be allergic to one thing.
The antibodies responsible for allergies also take care of cleaning up any parasites that your body…
