The genetics of intelligence and social outcomes in a Hungarian twin sample

Abstract

Most previous research found that within-family resemblance on social outcomes and intelligence is mostly due to genetic factors with a limited role of the shared environment, with the exception of educational attainment. Hypotheses about a gene-environment interaction with SES, with a presumably smaller role of genetic factors in families with low social status, have been only partially confirmed. However, these results do not necessarily generalize to all societies, and data from Central or Eastern European countries is currently deficient. In the current work we replicate using data from the Hungarian Twin Registry that intelligence, income, and educational attainment are substantially heritable, with limited role of the shared environment. In contrast to studies in Anglo-Saxon or Western European countries, we found an influence of the shared environment on standardized high school test scores, especially history. Both genetic and shared environmental (but not nonshared environmental) correlations were substantial, in line with generalist genes and shared environments but specific nonshared environmental effects. The results show that the heritability of social traits is observable in Central/Eastern Europe, but they highlight a potentially problematic aspect of Hungarian high school final tests, as students' family of origin appears to be a potent determinant of grades.