__Heredity.__ Your father and mother each have a 30-40 % risk of inheriting allergies, and if both parents have them, up to 70 %. Accordingly, the more adults that have [allergies](https://ul.orna.me/KOge/librarydisease?id=21) the more children inherit the disease. __The desire for sterility.__ In 1989, scientist David Strachan formulated the so-called "hygiene hypothesis". ===The hypothesis is that the less frequently people encounter bacteria in everyday life, the lower the bacterial and viral load, and the higher the risk of allergies. Statistics confirm the theory: rural residents have allergies much less frequently than city dwellers. __Cesarean section delivery.__ When the baby passes through the birth canal, its body is populated with bacteria and microorganisms that form a unique microbiome, and 70 % of the immune system is centered around the gut. "Caesareans" do not have this, and so there are more allergy sufferers among them. __Dietary restrictions on children.__ By protecting babies from possible food allergens and restricting their diet, parents do not allow the immune system to learn how to adequately respond to a possible threat. This can lead to allergies in the future. __Excessive variety.__ Today, we have hundreds of options for food and a vast number of medicines, dietary supplements, chemicals, and supplements. However, not all of it fits together. For example, if you are not allergic to wheat protein but once ate a bun and took some medicine, you created a combination that the body is not able to "digest" so easily, which triggered an allergic reaction. __Travel to exotic countries.__ Today, people travel much more often and farther than in the past. When you find yourself in a different climate, with a different environment, food, and animals, it's easy to encounter new allergens. __Stress.__ This is a hallmark of our times. Stress lowers the immune system, which can cause eczema, dermatitis, and asthma attacks. Studies have noted that asthmatic students have a 30 % increase in the frequency of attacks. __Deterioration of the environmental situation.__ Increased concentration of chemicals in the air increases the activity of natural allergens. Substances disrupt the function of the epithelial barrier of cells, which can give rise to allergies. Indoor concentrations of chemicals from heating and detergents are 2 to 5 times higher than outdoors, which also provokes allergic reactions. __Advanced diagnosis.__ The number of allergy sufferers is also increasing because allergies have become better diagnosed, and people have become more aware. People are better able to distinguish an ordinary runny nose from an allergic one, so they go to the doctor.