Back in the 19th century, pioneer Italian criminologist Cesare Lombroso claimed that criminality was genetic. Born criminals were throwbacks to an earlier, less evolved form of humanity and could be identified by physical feature. True criminals had sloping foreheads, jug ears, large chins, fleshy lips, and hard shifty eyes. He attempted to analyse these with craniometers and calipers.

Eventually Lombroso’s work fell out of favour, as it was based on social Darwinism and led to racism and eugenics. But now it may be making a comeback in a more nuanced form. In the latest issue of the American Sociological Review, Guang Guo, of the University of North Carolina-Chapel Hill, claims that delinquency is at least partially genetically determined. He has identified three genes which predict delinquency, at least when linked to certain environmental conditions. For instance, there appears to be an interaction between repeating a school grade and the MAOA*2 repeat (2R) allele in adolescent boys.

Guo acknowledges this his work has enormous policy implications. Genetic evidence, he says, points to the existence of hard-wired genetic differences. “For example, evidence of genetic propensities for criminal behavior may be used to challenge a basic assumption of the US legal system: individuals have free will and consequently are held legally responsible for their behavior. If an individual’s free will is weakened by innate propensities for criminality, should the person not be held fully responsible? In such a case, punishments like the death penalty might seem cruel and unusual.

“The same genetic evidence may also work against a defendant. In some states, sexual predator laws indefinitely jail offenders who have been convicted of multiple sex crimes against children, for fear the perpetrators may harm children again if released. Conceivably, genetic evidence could be used to suggest that individuals predisposed to commit sex crimes should not be released. Responsible use of genetic evidence in these and other ethical, legal, and social issues remains an unresolved challenge.” ~ American Sociological Review, August