GENETIC AND ENVIRONMENTAL-INFLUENCES ON TEMPERAMENT IN MIDDLE CHILDHOOD - ANALYSES OF TEACHER AND TESTER RATINGS

Parent ratings of temperament in infancy and childhood yield evidence for genetic influence in twin studies but not in adoption studies. The present study used the sibling adoption design to investigate teacher and tester ratings of temperament in middle childhood. When each chil d was 7 years old, ratings on the Colorado Childhood Temperament Inven tory were obtained from a teacher and tester for more than 50 pairs ea ch of adoptive and nonadoptive siblings in the Colorado Adoption Proje ct. Significant genetic influence emerged for both teacher and tester ratings of Activity, for tester ratings of Sociability, and for teache r ratings of Emotionality. Results obtained from bivariate genetic ana lysis suggest that the modest covariance between teacher and tester ra tings of Activity is entirely mediated genetically. Except for teacher ratings of Attention Span, evidence of shared family environment was nonsignificant, despite the power of the sibling adoption design to de tect it.