Causes of Stuttering Stuttering usually starts between **2 and 6 years of age**. Many children go through normal periods of disfluency lasting less than 6 months. Stuttering lasting longer than this may need treatment. There is no one cause of stuttering. Possible causes include the following: Family history. Many people who stutter have a family member who also stutters. Brain differences. People who stutter may have small differences in the way their brain works during speech. You cannot always know which children will continue to stutter, but the following factors may place them at risk: Gender. Boys are more likely to continue stuttering than girls. Data are currently limited to individuals who identify as male or female. Age when stuttering began. Children who start stuttering at age 3½ or later are more likely to continue stuttering. Family recovery patterns. Children with family members who continued to stutter are also more likely to continue.