Medically reviewed on May 17, 2023 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
Table of contents
What separates those with food allergies from those without? Generally, the difference lies within a person’s immune system.1 People with food allergies have abnormal responses to proteins found in certain foods, such as nuts, grains, and milk. Accordingly, the immune system will attack the “invader,” often triggering an inflammatory and/or immune response.
That said, babies aren’t naturally born with food allergies; food intolerances develop over time. Nevertheless, some children are genetically predisposed to certain allergies.  Environmental factors may also play a part. 
Read on as the complexities of food allergies and how they may be tied to genetics is explored.
Food allergy symptoms develop when the immune system over-defends the body against a certain allergen. This process involves the production of immunoglobulin E (IgE), an antibody that binds to certain immune cells to activate chemicals like histamine. Histamine plays a primary role in the body’s inflammatory response and, accordingly, in allergic reactions. 
When the body first comes into contact with the allergen, an allergic reaction rarely occurs. A second, third, or fourth exposure, however, will activate an allergic response. That’s because the IgE antibody will immediately recognize the allergen, and fight against it. 
So, how long does a food allergy reaction last? That depends, some may only have it for a few hours or days, and in severe cases, an IgE-mediated allergic reaction to food can lead to anaphylaxis, which can be life-threatening. 
In children, it’s believed that oral immunotherapy, or regular exposure to certain food allergens, such as peanuts, shellfish, wheat, or soy, may decrease the risk of developing a food allergy.  Accordingly, avoiding certain foods may predispose a child to developing a food allergy, since their immune system will be unfamiliar with the protein and may believe it to be a harmful invader.
Below are some examples of allergenic foods:
The rise of food allergies in recent years has pointed to another possible cause: genetics. 
That said, the exact genetic mechanisms involved in food allergies are not fully understood. Researchers have, however, identified one genome that may predispose a person to a peanut allergy, which harbors in the Human Leukocyte Antigen (HLA)-DQ and HLA-DR genes. 
Not everyone with this genome will develop a peanut allergy—environmental factors also come into play. Lack of exposure to the allergen may reduce the risk of an allergic reaction.  In other words, if you never come in contact with a peanut there is very little chance of your body activating an immune response against it.
Likely, allergic reactions develop as a result of changes in the epigenome, which is established in utero and determines how genes are expressed.  The epigenome can be altered throughout one's lifetime, which can explain why some people develop food allergies later in life.3 That said, it’s particularly sensitive to environmental factors during one’s early life. 
It’s also believed that a genetic predisposition may cause some individuals immune system to dysregulate, which may affect the system’s response to certain proteins found in foods. 
Other studies have found that individuals with a family history of allergies, including food allergies, are more likely to develop food allergies themselves.  So, a child with two parents who have a food allergy is more likely to develop a food allergy, compared to a child with only one parent who has an allergy or with no parents with food allergies.
However, it is not guaranteed that the child will inherit the specific food allergy. The risk factors can vary widely depending on the particular allergy and other genetic and environmental factors. It’s recommended to consult with a healthcare provider or an allergist for a more personalized assessment.
While a genetic predisposition can play a role in food allergies, environmental triggers also significantly influence the development and severity of allergic reactions or symptoms. Exposure to allergenic substances can exacerbate allergic responses in individuals with food allergies.  These substances may include: 
This phenomenon, known as ‘cross-reactivity’, occurs when proteins from different sources share similar structures, leading to an immune response triggered by both the food and the environmental allergen.  It most often occurs in a condition known as "oral allergy syndrome". 
Gut microbiota—microorganisms residing in the digestive tract— may also play a role in the development of some food allergies. 
Research found that alterations in gut microbiota composition and diversity during early life may contribute to the development of food allergies, and children with food allergies have distinct gut microbiomes.8 Imbalances in the gut microbiota are often associated with several factors, such as: 
Certain beneficial bacteria in the gut can also help regulate immune responses and promote tolerance to potential allergens. 
So, are food allergies genetic? While not fully understood, researchers believe that genetic factors may play a role in the development of certain food allergies. That said, environmental factors, diet, medical conditions, and body composition can also contribute to the development of food allergies.
If you believe you may be predisposed to certain food allergens, the Everlywell at-home Food Allergy Test can measure your body’s IgE reactivity to several proteins found in food, including but not limited to almond, cow’s milk, shrimp, and soy. Once you receive your results, you can speak to a healthcare provider about next steps.
Take the first step today.