Why is my brother allergic to peanuts and I’m not?

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Question: Why is my brother allergic to peanuts and I’m not?

Answer: While food allergies can definitely run in the family, a recent study revealed the surprising fact that firstborn children can be almost twice as likely to develop food allergies than their younger siblings. This may be due to changes in their mothers’ immune systems after multiple pregnancies. Another study showed that the siblings of kids with certain food allergies have less than a 15% chance of having the same allergy. In fact, for peanut allergies specifically, only 3.7% of siblings had the same allergy. Even identical twins don’t always share the same food allergies, which helps us understand that there’s more at play than mere genetics. For some reason, the immune systems in certain people simply overreact to certain types of food. No one knows exactly why. You have a slightly higher chance of developing a food allergy if you or someone in your immediate family already has other allergies, or asthma, or eczema. But there can be many other causes, as well. If you think that you or a loved one may be allergic to certain foods, consult with your healthcare provider to get tested. Treatments are available, and there are ways that people with food allergies can cope with living in this world and being social – checking food labels, telling those around them about their allergies, carrying adrenaline auto-injectors with them, etc.