Variant Of Dopamine Transporter Gene Protects Against Risky Illegal Behaviour

In the penultimate chapter of NOT A CHIMP I speculate about the role of variants in genes for dopamine, vasopressin receptor, serotonin transport and MAO-A, in underpinning an adaptive range of temperamental phenotypes in human populations, similar to the hyper-variability in these genes and in temperament observed in rhesus macaques. Here researchers look at variants of the dopamine transporter gene and find that one variant is much more protective than others against the likelihood of illegal transgressions and risky behaviour during adolescence and early adulthood. Here's the abstract (the journal is PLoS One which means you can freely access the whole paper):

This study tests the specific hypothesis that the 9R/9R genotype in the VNTR of the dopamine transporter gene (DAT1) exerts a general protective effect against a spectrum of risky behaviors in comparison to the 10R/9R and 10R/10R genotypes, drawing on three-time repeated measures of risky behaviors in adolescence and young adulthood on about 822 non-Hispanic white males from the Add Health study. Our data have established two empirical findings. The first is a protective main effect in the DAT1 gene against risky behaviors. The second finding is that the protective effect varies over age, with the effect prominent at ages when a behavior is illegal and the effect largely vanished at ages when the behavior becomes legal or more socially tolerated. Both the protective main effect and the gene-lifecourse interaction effect are replicated across a spectrum of most common risky behaviors: delinquency, variety of sexual partners, binge drinking, drinking quantity, smoking quantity, smoking frequency, marijuana use, cocaine use, other illegal drug use, and seatbelt non-wearing. We also compared individuals with the protective genotype and individuals without it in terms of age, physical maturity, verbal IQ, GPA, received popularity, sent popularity, church attendance, two biological parents, and parental education. These comparisons indicate that the protective effect of DAT1*9R/9R cannot be explained away by these background characteristics. Our work demonstrates how legal/social contexts can enhance or reduce a genetic effect on risky behaviors.