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Causes of Stuttering

Updated: Nov 4

No one speaks with perfect fluency all the time. Everyone occasionally says “um” or “like,” repeats a word, or pauses to find the right one. These normal disfluencies differ from stuttering, where interruptions in speech occur more frequently and can impact communication, confidence, and emotional well-being.


For people who stutter, these moments can bring feelings of loss of control, frustration, shame, or even trauma. For some, stuttering resolves in childhood; for others, it continues through adulthood. Why does this happen?


Researchers agree that stuttering results from a combination of factors — including genetics, language development, environment, and brain structure and function (Smith & Weber, 2017). These factors interact dynamically to influence how speech develops and is produced.


Stuttering and Language Development


Stuttering most often begins between the ages of two and five, when speech and language are developing rapidly. During this stage, children’s brains are learning to coordinate complex skills such as vocabulary, sentence construction, and speech motor control.


Researchers believe that interactions among genetic predisposition, natural language growth, and neurological timing differences contribute to whether stuttering emerges or continues over time.


For some children, stuttering naturally resolves on its own, while for others, it remains a part of how they communicate. This stage of development places high cognitive and motor demands on speech, and for children predisposed to stutter, those demands may temporarily or persistently disrupt fluency.


Genetic Factors


Family histories consistently show that stuttering runs in families. Children who stutter frequently have relatives who also stutter, and identical twins (who share all genes) exhibit more similar stuttering patterns than fraternal twins.


While no single “stuttering gene” has been identified, researchers have linked several gene variants to the condition. These genes influence how the brain develops and maintains the pathways responsible for speech and motor coordination.


Stuttering also shows a gender difference: it affects males more than females, and females are more likely to recover before adulthood.


Genetic predisposition alone does not determine outcome—it interacts with brain organization, language growth, and environment.


Brain Activity in People Who Stutter


The prevailing theory suggests that neurological organization influences both the onset and persistence of stuttering.


Brain imaging studies reveal differences in how people who stutter plan, time, and execute speech:

  • Greater right-hemisphere activity, paired with reduced activation in traditional left-hemisphere speech centers.

  • Differences in white-matter connections that link motor and auditory areas of the brain.

  • Less efficient auditory feedback processing and slightly slower sensory-motor reaction times.


These neurological findings reinforce that stuttering is not psychological—it’s rooted in how the brain coordinates language and movement.


Emotions and the Environment


Children who experience negative listener reactions or teasing may develop fear, shame, or avoidance behaviors around speaking. Attempts to hide or prevent stuttering can increase physical tension, further disrupting fluency.


Although emotional factors and nervousness do not cause stuttering, they can amplify its frequency or visibility. Supportive, patient environments—where communication is valued over speed—help children and adults communicate with more confidence.


Characteristics Associated with Persistence


Between 5% and 8% of preschool children develop stuttering, but roughly 80% recover naturally.


Children may be more likely to continue stuttering if they:

  • Are male

  • Have a family history of stuttering

  • Are older at onset

  • Exhibit frequent stuttering-like disfluencies or speech-sound errors

  • Demonstrate variable or extreme language skills


These factors don’t guarantee persistence but can help SLPs identify children who may benefit from early intervention.


Acquired Stuttering


While most stuttering begins in early childhood, some adults develop acquired stuttering following neurological or psychological events.


  • Neurogenic stuttering may occur after stroke, head injury, or degenerative disease.

  • Psychogenic stuttering can emerge after emotional trauma or stress.


These cases differ from developmental stuttering and require specialized assessment to determine the underlying cause.


Child in a light blue shirt talking to an adult on a gray sofa. The room feels cozy and warm, with soft lighting from a window.

Common Myths About Causes


There are many myths surrounding the origins of stuttering. It’s vital to understand what does not cause it:

  • Stuttering is not caused by parenting or how parents react to speech.

  • Stuttering is not a psychological problem, though it can have emotional effects.

  • Stuttering does not reflect low intelligence.

  • Stuttering is not caused by bilingualism, though fluency may vary across languages.

  • Stuttering is not caused by nervousness or anxiety.


Most importantly, stuttering is no one’s fault.


Learn More & Get Involved

Understanding the multifactorial nature of stuttering helps professionals and families respond with empathy and evidence-based care.



References


Original material provided by: Leslee Dean, M.A. (Latin American Studies), MS-SLP student, Florida International University, and Angela M. Medina, Ph.D., CCC-SLP.Revisions provided (01 / 2024) by Caitlin Franchini, MS, CCC-SLP, and Dr. Megan M. Young, CCC-SLP.


Last Updated: October 2025

Author: National Stuttering Association Marketing & Education Team with contributions from Nicole Kulmaczewski, MS, CCC-SLP and Jacqueline Toscano, SLP.D. CCC-SLP


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