Understanding the role of the environment in the dynamics of gene-environment interactions shaping psychological traits of the child is one of the central issues of contemporary psychogenetics. The socioeconomic status of the parents (education in particular) is a critical factor regulating the share of environmental and genetic influences on the child’s cognitive abilities. This work is a study of phenotypic associations between the results of the subtests of the Heidelberg Speech Development Test designed to measure children’s speech and language competence, by computing genotypic and environmental correlations between its components. Children were divided into groups based on the educational level of their mothers (medium and high); each group was analyzed separately. For our analysis we used the twin method: the group of twins born to mothers with medium-level education included 17 monozygotic and 11 dizygotic twin pairs; the group of children born to highly educated mothers was comprised of 17 monozygotic and 22 dizygotic twin pairs. All children were aged from 7 years to 8 years and 11 months. Family report forms revealed an association between maternal education and individualized approach to the upbringing of each of the twins. It was shown that in families with highly educated mothers, differences in the upbringing strategies improve the development of language and speech competencies of the child, strengthen the relationship between various language competencies, increase the contribution of the genotype to and decrease the role of the general family environment in this relationship.