THE GENETIC ASPECTS OF HIGH INTELLIGENCE

A cohort of 71 pairs of twins was studied in a project which started within the decade 1965 to 1975. The total level of intelligence (global IQ) and the level of particular intellectual components have been examined annually since the twins were two years of age. The data were analysed by comparing monozygotic and dizygotic twins. The results revealed that high intelligence is influenced much more by hereditary than exogenous factors. Furthermore, there is an irregularity in the development of intellectual level from childhood to adulthood. Consequently, decision making about children cannot be carried out on the basis of a single IQ evaluation. A cluster analysis demonstrated the importance of hereditary factors not only on intellectual level, but also on the pattern of intellectual development.