There can be a difference between true allergies and sensitivities. Allergies are not hereditary. They can come and go through life depending on how well the adrenals are working. When we are exposed to allergens the body will try to fight that allergen with the release of epinephrine and corticosteroids from the adrenal glands. If all is working properly then sufficient levels of these compounds are released in response. The epinephrine is our antihistamine and anti-leukotriene. The corticosteroids are the body's anti-inflammatories, and immune modulators that prevent over reaction to the allergens. This is why we are all exposed to allergens, but we do not all have allergies. This is also the reason children can "outgrow" their allergies since the adrenals need time to mature. And why allergies, including asthma, are more prevalent at times of high stress or when other things are taken that also suppress adrenal function such as stimulants and steroids.
In hereditary conditions like celiac there are antibodies being generated that tag the villi in the intestines for destruction. So this is different from allergies.