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

Most previous research found that within-family resemblance on social outcomes (such as educational outcomes and income) 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 a low and potentially zero role of the shared environment. In contrast to previous studies in Anglo-Saxon or Western European countries, we found a substantial influence of the shared environment on standardized high school test scores, especially history and literature. Both genetic and shared environmental (but not nonshared environmental) correlations were substantial, in line with generalist genes and shared environments but specific (potentially error-related) nonshared environmental effects. The results show that the substantial heritability of social traits is observable even 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 causal determinant of grades at least in some subjects.