Academic Achievement in Twins: Extreme Group Analysis

The aim of this study was to compare groups with extreme values of scholastic achievement and analyze the causes of individual differences in cognitive development.The sample comprised twins (2282 pairs) and singletons (3907 children) of school age (1-11 grades). The sample is representative to Russian Federation population for region of residence, number of children in the family and parental socio-demographic status.It is shown that gender, family structure and peculiarities of intra-pair relationship are significant for academic achievement of schoolchildren.