ABSTRACT
Conclusions from the heredity-environment controversy have been used to support contrasting positions regarding politics, race, class and caste. Although evolution theory predicts genetic differences in human capacities, a simple quantitative estimate of the relative contribution of heredity and environment is impossible as that figure depends on a variety of factors. The twin heritability studies underestimate the effect of the environment because of methodological biases. The person-situation debate draws attention to the interaction between person variables (explained by genetics and earlier experience) and situation variables (i.e., the present situation), an interaction explained by the non-linear interaction of person and situation (NIPS) model. Epigenetics shows how genes are expressed through environmental influences and explains how adverse childhood experiences create a range of health-related problems including psychological problems. Research on intergenerational epigenetic inheritance shows how the mother’s experiences affect gene expression of the developing foetus, and transgenerational epigenetic research shows how expressed genes of mothers and fathers are passed down through subsequent generations. The nature-nurture debate arose out a desire to support racist and discriminatory practice based on a simplistic idea about the mechanism of inheritance, but research has demonstrated the long-lasting effect of environment on human well-being.
