First off, what are allergies? Now your body is a working machine and has these wonderful soldiers (immune system) constantly protecting our body from foreign objects (substance). Great right, but not if our immune system reacts to the slightest thing that may be harmless to most people and mistake it for a harmful object.
Substances or lack of better term allergens, that cause allergic reactions are dust, dust mites, pollen, mold, pets, cow’s milk, eggs, fish, shellfish, peanuts, tree nuts, soy, wheat, insects, medicines, and chemicals.
These allergies can be passed down through genes or developed throughout the years. I for one used to enjoy good old cow’s milk and as I got older (in the 30’s) I became Lactose Intolerant. While on the other hand, I was born with seasonal allergies which have now passed on to my kids as well. So allergies can come out of nowhere or just be a pain in your entire life’s existence.