Heredity of cognitive functions and personality in twins.

BACKGROUND AND OBJECTIVE: The inheritance of cognitive functions and personality is still a problem under investigation. A classical method, investigation of twins, is often used to find relative contributions from genetics and the environment to quantitative traits. The aim of this study was to investigate a possible influence of heredity on cognitive functions (by applying the Raven test) and personality traits (according to the Eysenck's theory) in twins. MATERIAL AND METHODS: In total, 139 pairs of same-sex twins were investigated. The zygosity of the twin pairs was confirmed through genotyping with 15 molecular DNA markers. Constructive thinking was assessed using the Raven test. Personality assessment was conducted using the Eysenck Personality Questionnaire (EPQ) in Lithuanian. RESULTS: The difference in the total number of incorrect solutions between monozygotic (MZ) and dizygotic (DZ) twin pairs younger than 15 years was not significant; however, in the group older than 15 years, this difference was found to be significant. Based on the total number of incorrect solutions, the concordance in the MZ twins was greater than in the DZ twins. The same tendency was found with cumulative EPQ scores on the extraversion scale. CONCLUSIONS: The results imply that the quality of cognitive functions and personality traits (extraversion) can be influenced by heredity. This confirms previous findings on the heritability of cognitive factors and personality traits.

[Human Y chromosome: structure and biological role]. / Zmogaus Y chromosoma: struktura ir biologinis vaidmuo.

Y chromosome differs from other human chromosomes. It is found in cells of the male persons only. Different human phenotypes are associated with non-recombinant region of Y chromosome. This chromosome is of great significance in the human sex determination and the development of male gametes (spermatogenesis). Testes develop in embryos which have the Y chromosome, and ovaries develop in embryos which have no Y chromosome. SRY (sex-determining region of the Y chromosome) gene determines the male phenotype. Translocation of this gene determines sex reversal. The aim of this article was to review the structure and biological functions of the human Y chromosome.