ABSTRACT
While some instances of developmental disabilities are isolated cases within families, many other developmental disabilities display a familial pattern of transmission. Children with mild mental impairment have been shown to have siblings with general intelligence scores significantly below the average of the population, near the 26th percentile (1). Similarly, quarter of first-degree relatives of children with communication disorders also report communication disorders (2). Siblings and parents of children with reading disabilities have been shown to perform significantly more poorly on
measures of reading than parents and siblings of nonreadingdisabled children (3).
