PARENTAL RATINGS OF BEHAVIOR PROBLEMS - A TWIN AND GENERAL-POPULATIONCOMPARISON

Generalization from twin studies relies on the assumption that liabili ty to develop the disorder which is studied is influenced by similar f actors in twins and singletons. The present study examines the impact of pre- and perinatal factors on parental reports of behaviour problem s in 1832 twins, and compares level of attention problems, internalizi ng and externalizing behaviour in the twins with 723 children and adol escents from a general population sample. The modest influence of rela tive birth weight and birth order on level of attention problems in tw ins did not contribute to significant differences between twins and th e general population sample. The levels of attention problems and exte rnalizing behaviour was similar and there was a modest age dependent d ifference in internalizing behaviour. An increased variance was found for externalizing behaviour in twins.