Q: Our identical twin girls are 2 1/2 years old, and one has an allergy to tree nuts. Our new allergist’s nurse said it’s common for identical twins to have the same food allergies.
I’d been contemplating introducing almonds to the non-allergic twin, but now I’m wondering if I need to request allergy tests first. What would you suggest?
Dr. Sicherer: My group at the Icahn School of Medicine at Mount Sinai reported a study on peanut allergy and found that 64 percent of identical twins shared the allergy.
By contrast, the rate of shared peanut allergy for fraternal twins was only 7 percent, which is a rate similar to that among different aged siblings.
We do not have data for each individual food or nut (since tree nut is the allergy you’re concerned with). But we may assume that, in general, there is a higher rate of specific shared allergies among identical twins.
When to Test
You would likely feel more comfortable testing before serving your daughter the specific nuts to which her sister has already had a proven allergy. It is worth discussing this more with the family’s allergist, who knows the details about the allergens in question, in order to determine which nuts to test.
If these had been fraternal twins or siblings of different ages, I would not suggest testing the sibling without considering more about her personal dietary history and food allergy risk factors, such as eczema or other allergic conditions.
Dr. Scott Sicherer is a practicing allergist, clinical researcher and professor of pediatrics. He is Director of the Jaffe Food Allergy Institute and Chief of Pediatric Allergy and Immunology at the Icahn School of Medicine at Mount Sinai in New York. He’s also the author of Food Allergies: A Complete Guide for Eating When Your Life Depends On It.Submit a Question View all posts by this medical expert.