Around a quarter of the population suffers from some form of allergic disease and the number is increasing. Although allergies can develop at any age, they most commonly show up during childhood or early adulthood. A search of family medical histories of a child with allergies will usually turn up a close relative who also has allergies. If one parent, brother, or sister has allergies, there is a 25 percent chance that a child will also have allergies. The risk is much higher if both parents are allergic. But the child will not necessarily be allergic to the same substances as the parents, or always show the same type of allergic disease (e.g. allergic rhinitis, asthma or eczema).
