Food allergies can appear in anyone and at any age, although they are more frequent in the young population. The difference in the size of the reaction that occurs is related to the nature of the specific protein to which you are allergic or allergic.
There are factors that increase its allergenicity for different reasons, some not well known. People who take wheat flour and nothing happens to them, but if they consume some food made with wheat and exercise, it does hurt them. This is due to a protein called omega-5 gliadin (ω5G)