Are Allergies Hereditary?

Are Allergies Hereditary?

Maybe you or a member of your family was recently diagnosed with allergies. You probably have lots of questions. One of which might be, “Did I inherit this allergy?” or “Since I have allergies, will my children have allergies as well?” 

There is a pretty substantial body of evidence the tendency to develop allergies is often hereditary, which means it can be passed down through genes from parents to their kids. However, the exact allergy is not what is passed on, just the tendency to have allergies.  

Allergy is a defect in the immune system. The body does not correctly identify harmless protein as benign. Instead, it marks them in the same way it marks bacteria to build an immune response.

So when the body misidentifies the Fel d1 protein from the saliva and urine of cats as a germ, it creates an immune response. On every subsequent exposure to that protein, the immune system mistakenly thinks it needs to fight a germ.

This is why the symptoms of allergies so closely resemble a cold. Your body is conducting germ warfare against germs that are not there! 

So, the defect that is inherited is the tendency to misidentify the protein, but not the misidentification of a specific protein. In other words, if you are allergic to peanuts, your children may be able to eat peanut butter sandwiches all day but cannot be near a cat or dog.

Your child might have seasonal allergies to pollen but you are allergic to strawberries and your grandchildren might be allergic to rabbits. 

There was a study published in 2012 in The Journal of Allergy and Clinical Immunology that showed that not only were allergies inherited but they were also gender-related.

Until that time, it was commonly thought that allergies were maternal. That is, they were passed from mother to child. However, this study showed that a mother was more apt to pass allergies to a daughter and a father was more likely to pass allergies to a son.

In either instance, the specific allergy was not passed on (as in the previous example of peanuts and cats) but the tendency to have the allergy was passed from parent to child. This was also true for asthma and eczema as well. 

The one exception to this broad rule of thumb is penicillin allergy. If one or both parents of a child are allergic to penicillin, it is likely that the child will be allergic to penicillin. 

Also, twin studies have shown that in identical twins (twins with the exact same 25,000 genes) over 60% of the time if one twin is allergic to peanuts the other twin will be allergic to peanuts as well.

However, with fraternal twins (twins that share around 50% of their DNA) the rate was only 7%. So genes play a role, researchers just haven’t figured out exactly what that role is yet. 

Just because a parent has allergies doesn't mean that their kids definitely will get them.

Til Next Time!