Is There a Genetic Cause for Stuttering

Throughout this biology course and many others one is likely to be taught, a student learns that every trait we possess is a result of genes and therefore genetic information, however this may not be the case. A trait is described as a feature of an organism which is either expressed or genetically stored so to speak. In this case stuttering would definitely be a trait, as it is a feature of many humans which is currently expressed, however whether or not this trait is directly determined by genetics is another question entirely.

Stuttering is thought to be determined by some sort of a gene as it is very often passed down through families, and can occur in both twins of a pair of identical twins. Little evidence has been gathered as to where this suspected gene is actually located or what it does to induce stuttering, however studies involving a mutation of chromosome #12 could possibly explain some cases of stuttering. This falls in line with the Human Genome Project, which seeks to map all the genes humans possess. Although the project mapped out all human genetic information and nitrogenous base pairs, much of this data still has to be analyzed. This data could yield information on which chromosomes code for specific traits and how variations of these traits can affect humans. This can be done through analyzing other organisms like fruit flies which may have some of the same genetic coding to determine what this genetic information actually accomplishes.

Comparative Genomics, retrieved from:  National Human Genome Research Institute.

Although the definitive biological cause of stuttering has yet to be pinpointed, increased study of the human genome could bring this into light. Stuttering however is also thought to be a sort of psychological disorder. This could also be the correct explanation for a characteristic like this, as younger kids commonly ‘grow out’ of their stuttering as they age. In some cases a stutterer may not have any family members who stutter, however this could also be the case if family members were carriers of a stuttering trait. Some sources describe stuttering as a disorder which stems from ones inability or unwillingness to express emotions. Other sources say it is derived from tension caused by stress. This could be the case as a person has multiple sort of ways of talking. An example of this is someone like Dakota, who describes himself to talk with a more Southern American accent when visiting family in Southern America, however while in Canada Dakota talks without any noticeable accent. Something like this could also be the case with stutterers and stress, while in a more stressful situation a stutterer may speak in a more disfluent way than while relaxed. This is likely the case with stress as stuttering is known to reduce stress, blood pressure is an indicator of stress, and stuttering can lower blood pressure by up to 10%. So in a stressful scenario stuttering may be favoured on a physical level to reduce levels of stress.

Stuttering reduces stress, retrieved from: speech/language pathology

Again other sources state that stuttering is caused by interference in nerve signals between the two hemispheres of the brain. Still different sources state that stuttering is caused by the Amygdala, a region of the brain responsible for the fight or flight reactions of a person. The Amygdala is also responsible for a person’s emotional response to any sort of situation, this ties in to how the Amygdala can override any logical thinking of other areas of the brain with an overwhelming reaction. This is said to be capable of causing a stutter. Ultimately there are many theories which seek to explain this phenomenon, some explanations even claim that stutterers are more sensitive and are sort of ‘thrown off’ by typical expressions other people wouldn’t notice.

Ultimately it is likely somewhere in between these two possibilities of genetic or psychological causes where the answer lies. This is because neither of the two are conclusive, stutters don’t respond to placebos which indicates a genetic disorder, however people recover from stuttering which indicates some sort of psychological condition. Countless other arguments could be made for either side including how stuttering seems to be passed down through families or how stuttering worsens with stress. I think however it is likely some other trait like unnaturally high stress levels, or abnormal Amygdala behavior which ultimately lead to stuttering as a sort of side effect. Going forward I would like to know more about how traits and genetic mutations relate to humans, and also receive a broadened perspective on some of the facts of biology, like how every characteristic a person has is said to be coded for by genes.


One thought on “Is There a Genetic Cause for Stuttering

  1. Loved your post and articles to support your work, Lee!

    Perhaps the genetic linkage that mentioned stuttering’s potential connection to enzyme development could influence the development of the amygdala. Hopefully you can connect this learning to our gene expression unit in which we begin to explore the overlap of nature (genes) and nurture (environmental stimuli).

    When mentioning Dakota be sure to put the link to his blog page so a reader can go find out who you are referring to!


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