Babies aren’t born with food allergies, although some genetic factors can make a baby more likely to develop a food allergy. The good news is, there’s a way to help prevent your baby from developing a food allergy later in life. Here’s what parents need to know about family history and food allergies, and about reducing their baby’s food allergy risk. 

Many parents wonder: are babies born with food allergies? The answer to this question is a clear “no.” Babies are not born with food allergies. 

But are food allergies genetic? Yes, somewhat. Even though babies aren’t born with food allergies, there are some genetic factors that contribute to food allergies. Still, all babies are at risk for food allergies, regardless of their genetics. The good news is, there’s a way to significantly reduce the risk that your baby will develop a food allergy later in life. Here’s what parents need to know about genetics and food allergies, and about reducing their baby’s food allergy risk. 

How do food allergies develop?

Babies aren’t born with food allergies. Rather, food allergies develop over time.

Food allergies develop when a person’s tolerance to a food breaks down, or when they don’t build up a tolerance to a food quickly enough. 

Normally, our immune systems defend us from viruses and bacteria. But when someone develops a food allergy, their immune system over-defends the body in response to a food’s proteins. When someone's tolerance to a food breaks down, or its development is delayed, their immune system begins to treat the protein of that food as a foreign invader to their body. Every time they consume that food, their immune system prompts their body to develop an allergic reaction.

Food allergies develop through a combination of genetic and environmental factors. The main environmental factor is whether someone is exposed to a food at the right time. While exposure to foods during a certain immune window helps someone build up tolerance, lack of exposure to a food at the right time can increase someone’s food allergy risk. 

Even though food allergies are influenced by a lack of exposure to certain foods, food allergies don’t develop as a result of foods mothers eat, or avoid, during pregnancy. So, rest assured that your food choices during pregnancy will not cause your baby to develop a food allergy. Rather, food allergies develop due to other genetic and environmental factors. Let’s break down the genetic factors that can increase food allergy risk.

What genetic factors contribute to food allergies?

Family history of food allergy is one of the main genetic factors that can increase a baby’s food allergy risk. If a baby has an immediate family member (parent or sibling) with a food allergy, they’re at increased risk of developing one as well. While 1 out of 12 babies will eventually develop a food allergy, around 1 in 7 babies with a family food allergy history will develop a food allergy. 

The most significant factor that increases food allergy risk, though, is when a baby develops eczema. Eczema impacts a baby’s food allergy risk much more than having a family member with a food allergy. Up to 67% of infants with severe eczema, and 25% of infants with mild eczema, will develop a food allergy. This means that around 1 in 3 babies with eczema will develop a food allergy.

Risk Factors for Food Allergy Development

Like food allergies themselves, eczema also tends to run in families. If one of their parents has eczema, a child will have a 40%-50% chance of suffering from eczema, and if both of their parents have eczema, a child has a 50%-80% chance of suffering from eczema. 

Learn more from Mustela and Board Certified Dermatologist Dr. Latanya Benjamin:

This may be because genes play a crucial role in determining whether a baby will develop eczema. When these genes don’t work properly, it’s thought that a baby’s chances of eczema increase.

One of the genes that could influence a baby’s chances of getting eczema is called FLG, or the filaggrin gene. The filaggrin gene is responsible for making a skin protein. So, if it doesn’t work properly, it causes problems with the barrier function of a baby’s skin. According to recent research, this is thought to make a child more susceptible to eczema. 

But some children with eczema don’t have a problem with the filaggrin gene, because any of several genes (or other, environmental factors) could increase a baby’s eczema risk. We don’t yet know for sure what causes eczema. But regardless of what factors help cause it, if a baby has eczema, they are at the greatest risk of developing a food allergy.

How to reduce your child’s risk of developing a food allergy

Since babies aren't born with food allergies, there are steps families can take to decrease their baby's food allergy risk.

Thanks to the results of the landmark LEAP, EAT, and PETIT studies, scientists now recognize that babies enter a critical immune window for food allergy prevention around 4 months of age. Starting around 4 months of age, babies' immune systems begin to develop either a positive response (tolerance) or negative response to allergenic foods.

In most cases, this window appears to close around 11 months of age, although it seems to close earlier in some babies. So, the earlier you introduce allergy-causing foods to your baby, the better your chances of preventing a food allergy later in life. 

The critical immune window for food allergy prevention is 4-11 months of age...but the earlier you introduce allergy-causing foods, the better. 

If a baby eats common allergy-causing foods consistently during the critical immune window (4-11 months of age), they’ll build up tolerance to those foods, and they’ll be far less likely to develop a food allergy.

But as studies suggest, if a child isn’t exposed to allergy-causing foods until after this window, their risk of developing a food allergy increases. So, don't delay early allergen introduction!

The studies’ results showed that consistently introducing allergy-causing foods is just as important for prevention as starting early. So, for the best chance at preventing a food allergy, you'll need to introduce your baby to common allergy-causing foods (peanut, egg, and milk) 2-7 times per week for at least several months.

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These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease.