Are Food Allergies Genetic? An Allergist Weighs In

A food allergy is triggered when a person encounters a protein in food, known as an allergen. The immune system reacts excessively, releasing chemicals that lead to diverse allergy symptoms. Reactions can range from mild skin irritation to anaphylactic (severe and potentially life threatening) reactions.

The predisposition to developing allergies can be passed down genetically from one generation to the next. However, this doesn't mean that an allergy to a particular food will be passed down or that everyone with a food allergy inherit it from their parents.

Running in the family

Humans have 46 chromosomes (23 pairs) that they inherit from their parents. Children receive one of each pair of chromosomes at random from their mother and one of each pair randomly from their father.

The chromosomes contain genes, which express various traits and characteristics that can be passed along from one generation to the next. Because of the way these genes are handed down, one child might have brown hair like the mother while their sibling has blonde hair like the father. Just as siblings may inherit different hair colors, the predisposition to certain conditions, including food allergies, can be influenced by genetic factors.

How food allergies happen

A food allergy can occur when a person eats a protein in food called an allergen. The immune system then mistakenly regards this allergen as an invader and over-defends against it. This causes cells to release chemicals, resulting in various symptoms such as:

• hives
• swelling of the tongue and/or lips
• nausea
• vomiting
• abdominal pain
• diarrhea
• difficulty breathing
• coughing
• decrease in blood pressure

Nurture or nature?

Various studies suggest there may be a genetic predisposition to the development of food allergies, but the science in this area is still evolving. Researchers continue to seek a more definitive understanding of the specific genetic mechanisms involved in food allergies.

Complicating matters is the notion that allergies presenting themselves within families could reflect not only genetics but also shared environmental conditions.

A study released in 2000 indicated that the percentage of identical twins who had a peanut allergy was nearly 65%, while the ratio for fraternal twins was less than 10%, further suggesting a genetic component to allergies. The results reflected similar heritability of other allergic diseases such as asthma.

It is evident that some allergies have a family connection but it’s difficult for researchers to know exactly what percentage of allergies can be attributed solely to genetics. Other factors, especially environmental ones, can also be at play.

Airing it out

The increasing prevalence of food allergies has led researchers to conclude that environmental factors could also play a role in the susceptibility.

The Centers for Disease Control says children with food allergies are more than twice as likely to have other allergic conditions, such as environmental allergies like asthma, than children without allergies.

It is theorized that environmental factors such as air pollution, pollen exposure, animal exposure, environmental greenness, smoking, and our diets, may be some of the possible factors that may contribute to allergies including food allergies, according to the National Institute of Health.

While research suggests both a genetic and environmental predisposition to food allergies, the specific mechanisms remain a subject of ongoing study.

How to defend against food allergies

Identifying and managing food allergies can be helpful with the expertise of an allergist. The most helpful part of diagnosis is a person’s story about their reaction to food, and skin-prick tests and blood tests are common diagnostic tools.

Once identified, the primary approach involves avoiding the problematic food and having an epinephrine autoinjector readily available. Oral immunotherapy can also be considered in select patients, and there is ongoing research on a medication called omalizumab to help with managing food allergies. 

Currently there is no outright cure. Learning more about this condition and seeking personalized advice can significantly impact the lives of those affected by food allergies.