Caspi and colleagues investigated why some maltreated children grow up to behave antisocially while others do not, focusing on a gene affecting the enzyme MAOA. As part of a long-term study of a birth cohort, the researchers recorded whether boys had been maltreated in childhood and which version of the MAOA gene they carried (associated with higher or lower enzyme activity). They then assessed antisocial and violent behaviour in adulthood. Maltreatment was much more strongly linked to later antisocial behaviour in men with the low-activity version of the gene than in men with the high-activity version, who appeared more resistant to the effects of maltreatment. The gene alone, without maltreatment, did not strongly predict antisocial behaviour. The researchers concluded that genotype can moderate how strongly a childhood environment leads to later antisocial behaviour.
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References: Caspi, A., McClay, J., Moffitt, T. E. et al., 2002. 'Role of genotype in the cycle of violence in maltreated children.' Science, 297(5582), pp. 851 to 854. source adapted.
Discuss the following study with reference to two or more of the following concepts: bias, causality, measurement, and/or responsibility.
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Caspi et al. (2002) is a useful study for discussing causality, measurement and responsibility because its findings are often simplified in ways that the actual design does not justify. The study followed a birth cohort over time, recorded whether boys had experienced childhood maltreatment, identified whether they had