Genetic and Environmental Impact on Verbal and Nonverbal Cognitive Abilities: A Twin Study

The main focus of the present investigation on significance of twin study in examines the genetic and environmental factor which influences the verbal and nonverbal cognitive abilities of twins with the age group 6-8 years. The objectives of the designed twin study to assess the substantial genetic influence on the vernal and nonverbal cognitive abilities of twins. The Wechsler Intelligence Scale for Children WISC-R (Wechsler, 1974) was used to examine the both type of cognitive abilities namely: verbal and nonverbal. The estimates of heritability were 56 percent for verbal cognitive abilities and 60 percent for nonverbal cognitive abilities in Bhiwani district. In Hisar district the heritability estimates for verbal cognitive abilities was 53 per cent and for nonverbal cognitive abilities was 52 per cent. There was evidence for the gentic influence on verbal and nonverbal cognitive abilities of twins was more in Bhiwani location as compared to Hisar location and also concluded that the genetic influence was more on nonverbal cognitive abilities than the verbal cognitive abilities of twins.