Beyond Versus: The Struggle to Understand the Interaction of Nature and Nurture

7 Disarming the “Genetic Predisposition to Violence”: The Dangers of Mischaracterizing Interaction

Imagine scientists discovered a genetic predisposition to violence. That is, imagine they identified a gene that increases the risk of engaging in violent behavior, which in turn increases the risk of engaging in criminal activity. What would you do or want done with that scientific information? For example, if you were undergoing in vitro fertilization and selecting which embryo to implant for gestation, would you want the embryos genetically screened in order to avoid implanting the embryo with the genetic predisposition to violence? Or would you want the government to screen all newborns in order to identify those with the genetic predisposition to violence for purposes of monitoring and intervention? In 2002, a study was published that reported on the relationship between a particular gene and antisocial behaviors such as violence and criminality. The authors of the study were quickly credited with having found a “genetic predisposition to violence,” and bioethical commentators warned of and even advocated for screening for the genetic predisposition. The authors of the study were Terrie Moffitt and Avshalom Caspi, whom I introduced in chapter 4 and whose study on the serotonin transporter gene, exposure to stress, and the development of depression received so much scrutiny. A year before the depression study was published, though, they published the study on antisocial behavior, and while their study of depression has received the most attention from scientists, the study of antisocial behavior has received more attention from bioethicists interested in the ethical implications of their research. This chapter is about the results of that study on antisocial behavior and, in particular, the way in which the results of that study have been mischaracterized, with potentially dangerous consequences. I aim to show two things: first, that Moffitt and Caspi did not identify a “genetic predisposition to violence”; discussions of their results that employ such language fundamentally mischaracterize those results. And second, this 7 Disarming the “Genetic Predisposition to Violence”: The Dangers of Mischaracterizing Interaction 168 Chapter 7 mischaracterization has in turn misdirected the bioethical discussions of the ethical implications of their research results. In the first paragraph of this chapter, I asked what you would do or want done with scientific information about a genetic predisposition to violence. That was misleading, but intentionally so. It’s fascinating to wonder what we should do with scientific information that predicts criminal violence, and that fascination is nothing new. The danger arises when the fascination distorts our understanding of the scientific results being discussed. The Search for Biological Predictors of Criminal Violence Efforts at identifying biological markers that are predictive of criminality and violence are not new. In the 1870s, Francis Galton in England (introduced in chapter 1 as the father of eugenics) and Cesare Lombroso in Italy both sought physically defining characteristics of the “criminal man,” which would be predictive of criminal activity (Galton 1878; Lombroso 1876). Galton, for instance, developed a method he called “composite portraits.” With composite portraits, a photographer takes semi-transparent headshots of many different people who all fall into the same “type” and then layers those headshots on top of one another, thus generating the composite portrait of that type. The first “type” that Galton subjected to this method was violent criminals. With the composite portrait of the violent criminal at hand, Galton surmised, “The special villainous irregularities in the [individuals] have disappeared and the common humanity that underlies them has prevailed. They represent, not the criminal, but the man who is liable to fall into crime” (Galton 1878, 97–98). Galton’s reference to the disappearance of “special villainous irregularities” upon composite portraiture turned out to be more accurate than his reference to “the man who is liable to fall into crime.” Despite Galton’s extensive efforts, no physically defining “type” emerged for the criminally violent, as it eventually became clear that the composite criminal was essentially indistinguishable from the composite human (Pearson 1924, chapter 12). In the 1960s, the search for biomarkers of criminal violence shifted from physical attributes to chromosomal ones. British geneticist Patricia Jacobs and her colleagues studied patients institutionalized in Scotland’s high security State Hospital and reported that an unusually high number of those men carried an extra Y sex chromosome (Jacobs et al. 1965). Since females normally carry a set of XX sex chromosomes, and males normally carry the XY set of sex chromosomes, the thought was that these XYY Disarming the “Genetic Predisposition to Violence” 169...