INTELLIGENCE AND SCHOOL ACHIEVEMENT IN LIGHT OF THE GENETIC AND ENVIROMENTAL FACTORS

The main goal of this research was to examine influence of genetical and enviromental factors on the covariation between a measure of general intellectual ability and elementary and high school achievement. The research involved 340 male and female twins (168 monozygotic twins and 172 dizygotic twins) aged from 18 to 44 years. Multivariate biometric method was employed. Our findings confirmed positive phenotypic corelations between the general intellectual ability and elementary and high school achievement (.33-53). General genetic factor explains most of the achievement covariance (both in primary and secondary school) and general intellectual ability, which supports the assumption that the same set of genes determines the etiology of individual differences in the studied variables. Influence of a common shared enviroment explains the correlation between elementary school achievement and high school achievement. In addition, impacts of specific genetic factors that are unique to each construct also distinguish the tested variables.