Parent-based assessments of vocabulary, grammar, nonverbal ability, and use of language to refer to past and future were obtained for 8,386 twins at age 2. Of the children who had early language delay, 44.1% had persisting language difficulties at 3 years and 40.2% had persisting language difficulties at 4 years. (Contains references.) (CR)

A study involving 356 twin pairs with early language delay found environmental influences shared by both twins were more substantial than genetic factors. Heritability was significantly higher in those with persisting difficulties but only when assessed in terms of parental concern at 3 years or professional involvement at 4 years. (Contains…

This longitudinal monozygotic (MZ) twin differences study explored associations between birthweight and early family environment and teacher-rated behaviour problems and academic achievement at age 7. MZ differences in anxiety, hyperactivity, conduct problems, peer problems and academic achievement correlated significantly with MZ differences in…