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Environment/molecular genetics/Munafò: Main effects of genotype on personality phenotypes appear to be modest (Munafò, Clark, Moore et al. 2003)(1), as discussed above (>Personality traits/molecular genetics, >Extraversion/molecular genetics). One likely reason which may partially account for this is that genes interact with environmental influences to determine risk of any particular outcome, including personality. A gene × environment interaction occurs when the effect of exposure to an environmental risk factor is conditional upon an individual’s genotype, or vice versa (Caspi, Sugden, Moffitt et al. 2003)(2). Several studies of emotional disorders have tested for possible gene × environment interactions, which themselves may operate via personality traits given the known associations between personality and risk of psychiatric illness (e.g., Neuroticism and major depression).
Most studies of gene × environment interactions to date have focused on the serotonin transporter gene and stressful life events, with contrasting results. In the original study (Caspi, Sugden, Moffitt et al. 2003)(2), the 5-HTTLPR variant moderated the effect of stressful life events on the onset of depression among youngsters.
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Problems: One particular difficulty in such studies lies in the accurate specification of environmental effects. While genotype can be ascertained with a high degree of accuracy (subject to appropriate quality control measures), environmental effects are typically ascertained using either self- or parent-report measures. Moreover, the underlying constructs which are so measured (e.g., ‘stressful life events’) may be somewhat vague, and in fact represent a constellation of underlying constructs. See >Situations/Mischel, >situations/psychological theories.
For a recent critical review of gene × environment interactions, see Munafò, Durrant, Lewis and Flint (2009)(3).
1. Munafò, M. R., Clark, T. G., Moore, L. R., Payne, E., Walton, R. and Flint, J. 2003. Genetic polymorphisms and personality in healthy adults: a systematic review and meta-analysis, Molecular Psychiatry 8: 471–84
2. Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H., et al. 2003. Influence of life stress on depression: moderation by a polymorphism in the 5-HTT gene, Science 301: 386–9
3. Munafò, M. R., Durrant, C., Lewis, G. and Flint, J. 2009. Gene × environment interactions at the serotonin transporter locus, Biological Psychiatry 65: 211–19
Marcus R. Munafò,“Behavioural genetics: from variance to DNA“, in: Corr, Ph. J. & Matthews, G. (eds.)2009. The Cambridge handbook of Personality Psychology. New York: Cambridge University Press_____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
Philip J. Corr
The Cambridge Handbook of Personality Psychology New York 2009
Philip J. Corr (Ed.)
Personality and Individual Differences - Revisiting the classical studies Singapore, Washington DC, Melbourne 2018