TWIN LANGUAGE - A RISK FACTOR FOR LANGUAGE IMPAIRMENT

Retrospective parental report of earlier ''twin language'' was obtaine d for two groups of twins. Sample G consisted of 94 twin pairs between the ages of 7 and 13 years recruited through the school system as a g eneral population sample. Sample L consisted of 82 twin pairs between the ages of 7 and 13 years who had been recruited for a genetic study; of these twin pairs at least one of the twins had a speech-language i mpairment persisting to school age. Parental report of twin language w as higher (around 50%) for children with speech-language impairment th an for those with normal language (11%), Consistent with this, childre n with twin language obtained significantly lower mean language scores than other children, although their mean nonverbal IQ was equivalent. The exceptions were a handful of children whose parents described use of a ''private language'' that coexisted alongside normal use of Engl ish. These findings are consistent with the view that what is describe d as twin language is usually use of immature or deviant language by t wo children at the same developmental level.