Familial Incidence of Stuttering At least 25 studies have investigated whether stutterers are more likely to have relatives who stutter. The results varied so widely that they don't prove anything with certainty. [1] A 1940 study of five generations of an Iowa family, with stuttering in all generations, "proved" that the family had a "tone" [...]
Brain Imaging Studies Brain imaging studies have been done with adult stutterers but not with children who stutter. We don't know whether the neurological abnormalities found in adult stutterers cause stuttering or were caused by stuttering, i.e., whether growing up stuttering causes a normal child's brain to develop abnormalities. Different brain imaging studies found different [...]
Stuttering is a speech disorder with involuntary repetition and prolongation of sounds and syllables, and silent blocks in which the stutterer's vocal folds close and prevent the release of air and the production of sound. These obstacles negatively affect the pace, clarity, and prosody (emotional content) of speech. Stuttering includes abnormally high activity in the [...]