Stuttering affects individuals of all ages but occurs most frequently in young children between the ages of 2 and 6 who are developing language. Boys are three times more likely to stutter than girls. Most children, however, outgrow their stuttering, and it is estimated that less than 1 percent of adults stutter. Many individuals who stutter have become successful in careers that require public speaking. The list of individuals includes Winston Churchill, actress Marilyn Monroe, actors James Earl Jones, Bruce Willis and Jimmy Stewart, and singers Carly Simon and Mel Tillis, to name only a few.
Scientists suspect a variety of causes.
There is reason to believe that many forms of stuttering are genetically determined. The precise mechanisms causing stuttering are not understood. The most common form of stuttering is thought to be developmental, that is, it is occurring in children who are in the process of developing speech and language. This relaxed type of stuttering is felt to occur when a child's speech and language abilities are unable to meet his or her verbal demands. Stuttering happens when the child searches for the correct word.