The three genes that control levels of the neurotransmitter dopamine have been found to correlate with stuttering. These genes also correlate with Tourette's Syndrome, attention deficit hyperactive disorder (ADHD), and obsessive-compulsive disorder. These disorders appear to be caused by abnormally high levels of dopamine, in different parts of the brain. Research has not been done to determine whether all stutterers have these genes, or whether only some stutterers have these genes.

If you stutter, you are about three times more likely to have a close relative who stutters. Stuttering runs in some families. However, studies of the families of stutterers have failed to find simple Mendelian types of inheritance, such as sex-linked, autosomal dominant, or recessive.