All of us have fears of one kind or another, throughout our lives. Likewise, it’s completely normal for children of all ages, from the toddlers to the teens, to be afraid of something.
From a developmental perspective, it’s often easy to predict what children will fear at different ages. For example, even though your infant may have been very comfortable being passed from relative to relative, toddlers and preschool-age children may experience some separation anxiety. As your child becomes more aware that you and he are different beings, he naturally may have some anxiety about the idea of being separated from you. This is a pretty universal experience and usually passes over the course of several weeks or months.
Likewise, as children get older, they may express some fears about things like monsters, loud noises, the weather, the dark and things they see on TV. Even if your child previously slept in a completely dark room, or didn’t flinch during a thunderstorm, it's normal for the child to experience worries or get scared about different things at different times.