Attentional regulation in young twins with probable stuttering, high nonfluency, and typical fluency.

Purpose: Using a sample of 20,445 Dutch twins, this study examined the relationship between speech fluency and attentional regulation in children. A secondary objective was to identify etiological overlap between nonfluency and poor attention using fluency-discordant twin pairs.

Method: Three fluency groups were created at age 5 using a parent questionnaire: (a) probable stuttering (PS; N=826; 4.

Bivariate genetic analyses of stuttering and nonfluency in a large sample of 5-year-old twins.

Purpose: Behavioral genetic studies of speech fluency have focused on participants who present with clinical stuttering. Knowledge about genetic influences on the development and regulation of normal speech fluency is limited. The primary aims of this study were to identify the heritability of stuttering and high nonfluency and to assess the relative contribution of genetic and environmental factors to the correlation between these 2 fluency phenotypes.