[Summary of results of a study of heredity of intelligence in a sample of the Czech population. III. Longitudinal and genealogic study of twins and their families].

The author presents further results of the longitudinal study of inheritance of intelligence, its components and structure in twins. Summarized results are presented for the age period from 0-15 years as well as detailed results of individual components and the global IQ in the age group of 8-15 years. The paper follows after two previous ones published in 1988 where the applied methods and statistical evaluation were described. Evidence was provided that heredity of intelligence is involved in children from a very early age, i.e. 0-3 years. After the age of 4 heredity predominates markedly over environmental influences up to the age of 15 years investigated so far by the author. (A slight decline occurs during the prepubertal period-age 13 and 14 years.) The author found that in particular the following components of intellect are inborn: abstract thinking, logic, talent for mathematics, concentration, inquisitiveness. Very detailed tables are presented for possible comparison with data in the literature and data from adults. The author found that the development of intelligence from childhood to adult age is very irregular. This uneven character is also mostly inborn. Statistical evaluation revealed several basic types of developmental curves and extreme variants. This will, however, be discussed in another paper. The theoretical results can be used also in practice in school education, counselling psychologic and psychiatric out-patient departments.