Familial stuttering patterns are not related to one measure of severity.

The possibility of a genetic component to the severity of stuttering was investigated using data on 184 adult stutters and their families. Frequency of stuttering during a pre-treatment oral reading task was used as the severity measure for each of the index cases. Information on whether or not a relative ever stuttered was obtained on all first degree relatives. The family data variables, including sex and exact relationship, combined with birthdate and sex of index case were used in three types of analyses: multiple regressions, AID regressions, and stepwise regressions. None of the variables tested, including stuttering among first degree relatives, was a predictor of severity of stuttering in the index case. We conclude that this measure of severity is not related to the genetic factors which predispose to stuttering.