What makes one child allergic and another not? Why would one child be allergic to cats, dogs, fur, feathers, grasses, tree pollens, peanut butter? We all live on the same planet. We’re all essentially the same. If I took one individual with allergies and one without and boiled them down to their essentials, I would end up with approximately 32 kilograms of chemicals. The rest would be water, but the chemical composition would be the same in both individuals. The difference is most often seen in how one child’s body is able to adapt to her environment and another is not.