Sibship size and cognitive development of twins

Abstract

The influence of family structure (sibship size and birth order) on academic achievement in twins was analyzed. This study is a part of comparative research of academic achievement in school-age twins and singletons, which was supported by grant from the Russian Humanitarian Scientific Fund. Results show that family size (number of siblings) has negative correlation on cognitive development of twins; in families with higher SES sibship size less influence on scholastic achievement; birth order don’t influence on academic achievement of twins in families with 3 children.