If you have a food allergy, you may wonder about the likelihood of passing it on to your children. The thought of common foods like tree nuts, milk, or eggs triggering life-threatening reactions can be frightening for both you and your loved ones.

So, what exactly causes food allergies? Are they mainly influenced by genetics or are environmental factors to blame? Moreover, is there a way to prevent food allergies?

1. Food Allergies Often Run in Families

If you’re living with a food allergy, it’s natural to question whether your child may develop one as well. Additionally, you might wonder if siblings of children with food allergies are more likely to share the same allergy.

One method researchers use to determine if a biological condition is hereditary — or runs in the family — involves studies of identical twins because they have identical genes. Two studies on food allergies found that a twin is at a higher risk of developing food allergies if their twin sibling has one. In one study, researchers found that between 51 percent and 68 percent of twins whose twin siblings had allergies developed allergies as well. This trend proved especially true for peanut and shellfish allergies.

In families in which only one member has a food allergy, the risk of another family member developing the same allergy is low. However, when multiple family members have food allergies, the risk nearly doubles compared to the general population.

Certain types of allergy tests can help determine if you have a food allergy. One is the skin prick test, which checks skin reactions to allergens. A doctor may also use a blood test for immunoglobulin E (IgE) antibodies that your body makes against food allergens.

However, one large study found high rates of false positives — indicating an allergy when none exists — among siblings. This means that even though the siblings had increased antibodies or immune response to an allergy in a test, they didn’t actually have allergic symptoms.

While having a family history of specific food allergies may mean you have a greater chance of developing a food allergy, it is not predetermined.

2. Some Genes Are Associated With Food Allergies

Genes are the biological blueprint for bodies. Their code instructs the body to make proteins. This lays the groundwork for what our bodies look like and how they work. Variations in your genetic code can make you more likely to develop certain medical conditions, known as a genetic predisposition. Genes can also protect you against developing medical conditions.

Changes in the following genes have been linked to an increased risk of developing food allergies:

• DOCK8
• TGFBR1
• PGM3
• FOXP3
• WAS
• Desmoglein-1
• SPINK5

Research has shown that changes in a gene known as STAT3 can provide protection against developing food allergies.

Researchers have conducted genome-wide association studies (GWAS) to investigate genetic variations in a large population of people with food allergies.

However, the results of these studies have been inconclusive. This is because the gold standard for accurately determining whether someone truly has a food allergy is through oral challenges.

In an oral food challenge, you eat a small amount of the food you might be allergic to, with a doctor there to watch for any allergic reactions. This method provides more reliable and definitive evidence of a food allergy than relying only on genetic variations.

The genetics of food allergies is still mostly a mystery, unlike those of other immunological conditions such as asthma and atopic dermatitis (the most common form of eczema).

3. Environmental Conditions May Play a Role in Risk

While the cause of allergies is unknown, many environmental triggers have been linked to higher rates of food allergies. Members of the same family may be exposed to the same environmental conditions that are linked to food allergies.

Low Vitamin D Levels

Vitamin D plays an important role in supporting the immune system. Research indicates that a deficiency in vitamin D at 1 year of age can increase the child’s risk of developing a peanut allergy to 11 times that of the general population, and it can increase their risk of an egg allergy to four times that of the general population.

Additionally, people living closer to the equator, where sun exposure provides more vitamin D, have lower incidences of food allergies. However, it remains unclear whether vitamin D supplementation would help reduce these risks.

Lack of Oral Exposure to Allergens

Some evidence indicates that early oral exposure to food allergens, such as peanuts and eggs, could help prevent peanut allergies or allergies in general. Not eating enough of various foods during early development can slow down the immune system's proper growth, possibly causing heightened sensitivity reactions like food allergies later in life.

Studies have also found that when infants with eczema are exposed to allergenic foods, such as to peanut oil or peanut dust, via inflamed skin instead of orally, they can have a higher risk of developing an allergy to that food.

Biodiversity Exposure

Being exposed to a variety of plants, animals, and healthy bacteria in the environment can enhance a person’s immune system, particularly during early childhood. Studies have shown that children who grow up on farms and/or around animals — including dogs — are less likely to develop food allergies compared to those raised in urban settings or without animal exposure.

Additionally, research suggests that if a parent or caregiver cleans an infant’s pacifier by sucking on it instead of cleaning it with water or antiseptics, the infant has a lower risk of developing childhood allergic diseases. This finding further supports the idea that being exposed to different microbes at an early age is beneficial for strengthening immunity.

Airborne Irritants and Allergens

Researchers have found a link between airborne irritants and allergens, such as air pollution and pollen, and food allergies. An in-depth analysis of many research studies discovered a connection between increased air pollution levels and a higher rate of food allergies, although further research is needed.

Furthermore, pollen is an irritant for the lungs and respiratory system, potentially harmful to the airways. Higher pollen levels may increase the risk of developing peanut allergies and sensitization, although further research is needed.

4. Early Exposure May Prevent Food Allergies

Researchers are actively exploring ways to prevent food allergies, with significant breakthroughs involving exposing young children to specific allergens. One study found that giving infants food containing peanuts before their first birthday reduced their risk of developing peanut allergies. Similar studies have shown that introducing cow’s milk and eggs to an infant’s diet can also help prevent allergies to those foods.

In summary, exposing infants and young children to a wide variety of foods may be the most effective way to protect them from developing food allergies.

New Treatments for Food Allergies Are Being Developed

At the moment, there’s no cure for food allergies. However, new immunotherapies are being developed that would treat food allergies to make severe reactions less likely. Some of these therapies work based on the premise that regular, carefully controlled exposure to tiny amounts of an allergen over time can help your body’s immune system become less sensitive to it.

Another approach under development is the use of biologic drugs — human-made versions of immune system proteins — to target immunoglobulin E (IgE), a protein responsible for setting off allergic reactions. By binding with and neutralizing IgE, biologic drugs could help prevent the processes that lead to allergic reactions and life-threatening anaphylaxis.

Let your allergist know if you’re curious about these new treatments. They can let you know whether you or your child might be eligible once they become available.

Talk With Others Who Understand

On MyFoodAllergyTeam, the social network for people with food allergies and their loved ones, more than 39,000 members come together to ask questions, give advice, and share their stories with others who understand life with food allergies.

Do food allergies run in your family? Share your experience in the comments below, or start a conversation by posting on your Activities page.