GENETIC AND ENVIRONMENTAL INFLUENCE ON TEMPERAMENTAL TRAITS POSTULATED IN THE STRELAU’S REGULATIVE THEORY OF TEMPERAMENT IN A POLISH SAMPLE: DATA FROM CHILDREN, ADOLESCENTS, AND ADULTS
Faculty of Psychology, University of Warsaw, Warsaw (Poland)
The goal of the study was to assess the relative contribution of genetic and environmental factors to the phenotypic variability of temperamental traits in various age groups: children, adolescents, and adults. Th e traits considered were those proposed by Strelau’s Regulative Th eory of Temperament and included: Briskness, Perseverance, Sensory Sensitivity, Emotional Reactivity, Endurance and Activity.
Th e traits were measured using the Formal Characteristics of Behavior – Temperament Inventory (FCBTI) as well as the Temperament Inventory for Children (TIC). Th e study was conducted on three groups of participants, aged from 6 to 11, from 16 to 20, and from 17 to 64. All subjects were monozygotic and dizygotic twins reared together. Th e zygosity of twin pairs was assessed by the means of the selfreported Questionnaire of Twins Physical Resemblance. Th e data from the study on temperamental traits was analyzed by model fi tting using the method of maximum likelihood carried out by LISREL 8.03. It has confi rmed the heritability of the traits under study in various age groups as well as the existence of a signifi cant input of the specifi c environment factor into their variability. Th e data suggest a decrease of heritability with age and a simultaneous increase of the input of specifi c environment into the variability of the assessed traits.
Keywords: temperament, heritability, heritability change.