Anyone can get them, at any age. You could develop them as a child, or you might not have any symptoms until you’re an adult.
Why are some people sensitive to certain allergens while most aren’t? The major difference is in your genes. Allergies run in families. If your parents have allergies, you probably will, too. If one parent is allergic, your odds go up. If both are, your chances more than double. If neither parent is allergic, there’s still a small chance you’ll get them.
The world around you plays a part, too. You have to have a tendency and be exposed to an allergen before you develop an allergy. The more intense the exposure is, the more often you come into contact with the allergen, and the earlier in life this happens, the more likely you’ll be allergic.
Other things that may lead to allergies include smoking, pollution, infection, and hormones.