Nature vs. nurture is nonsense: On the necessity of an integrated genetic, social, developmental, and personality psychology

Abstract

The field of behavioural genetics unambiguously demonstrates that heritable individual differences exist and are important in explaining human behaviour. Despite this, some psychological perspectives ignore this research. If we wish to comprehensively understand the impact of parenting, the environment, or any social factor, however, we must engage with genetics. In this article, I review research that reveals that genes affect not only our personalities, but the way that we understand and react to the social world. Studies further reveal that notable life events are in part explained by genetic variance. I detail how this could be the case through active, evocative, and passive genetic correlations, and go on to argue that all complex psychological traits are likely the result of multifaceted gene by environment interactions. A mistaken belief that genetic influence implies genetic essentialism, and is therefore tantamount to prejudice, is raised as possible reason why heritability is often ignored in the social sciences. The article concludes with practical suggestions for how we can embrace behavioural genetics as our methods struggle to match the divine complexity of human existence.

Key words:

• attitudes—beliefs and values
• behavior genetics
• biological correlates
• development
• parent–child interactions
• social psychology

Funding information Australian Research Council Future Fellowship, Grant/Award Number: FT150100147

Funding information Australian Research Council Future Fellowship, Grant/Award Number: FT150100147

ACKNOWLEDGEMENTS

The author would like to thank Brendan Zietsch, Jemima Kang, and Matthew Hornsey for invaluable feedback on an earlier draft of this manuscript, as well as Luke Smillie, Nick Haslam, and two anonymous reviewers for their help in improving the manuscript. The author is supported by an Australian Research Council Future Fellowship (FT150100147).

Notes

Funding information Australian Research Council Future Fellowship, Grant/Award Number: FT150100147

1. Twin studies themselves rely on MZ and DZ twins having equally similar shared environments (the equal environments assumption). MZ twins, however, typically report that they are treated more similarly by others relative to DZ twins (although this appears to be a response to, rather than precursor of, similarity; Lytton, 1977). They also socialise together more frequently than DZ twin pairs (Kendler & Gardner, 1998). These differences, however, do not account for twin resemblance in depression, anxiety, or panic disorders. Genetic similarity, on the other hand, does (Kendler & Gardner, 1998; see also Kendler, Neale, Kessler, Heath, & Eaves, 1994). Furthermore, some examinations of personality concordance in twins have found magnitude of the correlation between MZ twin pairs raised together is similar to the correlation between MZ twin pairs reared apart (Tellegen et al., 1988)

2. Relying on none of the assumptions of twin studies, work using genome wide complex trait analysis has estimated that common single nucleotide polymorphisms can account for 15.2% of the variance in neuroticism (Realo et al., 2017), 25% of the variance in bipolar disorder (Lee et al., 2013), 31–41% of the variance in working memory (Vogler et al., 2014), 12% of extraversion (Vinkhuyzen et al., 2012), and 8.7% of the variance in major depression (Wray et al., 2018).

3. Another type of statistical gene x environment interaction has been widely studied, testing whether different traits are more or less heritable in different environments. The interested reader may look to an excellent review on these gene x environment interactions (Rutter, Moffitt, & Caspi, 2006), and as well as recent work from genome wide association studies (Rimfeld et al., 2018).

Additional information

Funding

Australian Research Council Future Fellowship