What is stuttering? Stuttering is a communication problem in which spoken words or sounds are involuntarily repeated, drawn out, not completed, or skipped. Stuttering is not unusual in young children between ages 2 and 7 years. Stuttering that begins during a child's intensive language-learning years and resolves on its own sometime before puberty is called normal disfluency. It is considered a normal phase of language development. Developmental stuttering is a speech problem that persists, gets worse over time, and causes embarrassment or discomfort. What causes stuttering? Stuttering results when the brain is unable to transmit messages properly. The exact cause of this failure is unknown, although genetics most likely play a role in some people. About 60% of people who stutter have other family members with the disorder. Environmental factors, such as a stressful environment, or biological influences, such as a developmental delay, may trigger stuttering, especially in people who have inherited the tendency to develop the disorder. In rare cases, stuttering develops as a result of brain damage, such as following a traumatic head injury or stroke.