LAUSR

Results of international comparisons of students in studies such as PISA (Program for International Student Assessment) and TIMSS (Trends in International Mathematics and Science Study) are often taken to indicate that mathematical education in Dutch schools is not appropriate for mathematically talented students. However, there has been no empirical study yet that investigated this hypothesis. If indeed, Dutch students with a genetic predisposition for high mathematical ability are not nurtured to their full potential, their mathematics performance should be more affected by environmental factors than that of children with a genetic predisposition for low mathematical ability. In behaviour genetics such a situation is termed genotype-environment interaction: the relative importance of environmental influences differs depending on students' genotypic values. To investigate genotype-environment interaction, we analyzed mathematics performance of 2110 Dutch twin pairs on a national achievement test. In the analysis we corrected for error variance heterogeneity in the measurement of mathematics performance through the application of an item response theory (IRT) measurement model. As hypothesized, results indicated that environmental influences are relatively more important in explaining individual differences in students with a genetic predisposition for high mathematical ability.