criminals An important figure in the early history of scientific criminology was the Italian Cesare Lombroso (1835–1909). Notoriously, Lombroso suggested that some (although not all) offenders are ‘born criminals’, characterized physically by a variety of morphological features reminiscent of lower primates, and therefore are atavistic throwbacks to an earlier stage in evolution. In the century since the publication of Lombroso's work, there has been a regular succession of ‘disclosures’ about links between crime and biology, many of which, like the atavism hypothesis, have been subsequently falsified. For example, in the late 1960s and early 1970s, suggestions were made that the small minority of males with an extra Y chromosome (in addition to the normal, single X and Y sex chromosomes) frequently exhibit extreme aggressive antisocial tendencies. More recent research fails to support these suggestions, though there is some evidence that the XYY anomaly is associated with factors (such as low IQ) that indirectly increase the likelihood of more minor antisocial acts.

Given this unfortunate intellectual history, it is hardly surprising that many sociologically-oriented criminologists have, in the past, denied, and some continue to deny, any link between biology and crime. Viewed dispassionately, the empirical evidence does not support such a position. However, the best evidence now suggests that links between biological characteristics and crime work in a probabilistic rather than a deterministic fashion, and that the extent of any genetic or other biological influence is, in general, only modest to moderate. Contrary to earlier speculations, there is no ‘criminal gene’ — nor indeed could there easily be, given that the concept of ‘crime’ is not a natural behavioural category, but a socially constructed concept, which varies between different societies, and in the same society over time.

How then might biology–crime links work? An example might be helpful. Research on criminal careers in several countries has consistently demonstrated, using both officially-recorded indices of crime and self-report studies, that a small minority of male persistent offenders is responsible for a very disproportionate percentage of all criminal acts. Longitudinal studies show that certain factors, identifiable at age 7–10, or earlier, can reliably differentiate subsequent persistent offenders, occasional offenders, and non-offenders. Among these identifiable factors are some that are unambiguously environmental, such as poor parenting. It is also clear, however, that pervasive, early-onset hyperactivity/inattention/impulsivity is associated with a greatly increased risk of criminal behaviour in adolescence and adulthood; and there is some evidence to link these traits with abnormalities of certain neurotransmitter systems in the brain. It is not hard to see that a trait of persisting impulsivity might be causally linked to later property crime (giving instant rather than delayed gratification) and violence (impulsive aggression). Yet, despite such links, we also know that hyperactive children reared in supportive and pro-social environments often do not become delinquent. For these and other reasons, predictive studies based on individual factors observable at age 7–10, while reliably predicting group differences, usually over-predict the incidence of subsequent persistent criminality.

This line of evidence and theorization strongly suggests that biological associations with criminality, while they certainly exist, can be understood properly only within a firm bio-social framework. To date, however, the specialization of academic disciplines, together with the unfortunate history of the search for a rigid link between biological characteristics and crime, has militated against much real progress in developing adequately detailed, interactive, bio-social explanations of crime.

An example illustrates the potential scope for such interactive explanations. Sociologists have observed that, in all modern societies, both official criminality and self-reported serious or persistent criminality is consistently associated with four variables: sex (males more criminal than females); age (peak age of criminality in adolescence); social class (lower class more likely to commit ‘street crimes’, such as burglary or robbery); and urban–rural differences (urban areas more criminal, even when other relevant variables are controlled for).

The standard research methods for attempting to infer possible genetic influences on criminality are studies of twins (looking for differences between genetically identical, monozygotic twins and non-identical, dizygotic pairs), and of adoptees (looking for similarities between the behaviour of the biological parents and their children, adopted and reared separately). Twin and adoptee studies have shown that inferred genetic effects seem consistently greater among samples of female offenders, adult offenders, higher-class offenders, and rural offenders. In other words, apparent genetic influences on criminality are proportionately greater within social contexts in which crime is generally low, and genetic factors diminish in influence as the group crime rate rises. The increased crime in general populations (disproportionately associated with urban, lower-class young men) is, then, largely produced by social factors.

There has been a significant renewal of serious scholarly interest in the field of biology and crime in the last decade. Given this, and the present underdeveloped state of interactive, bio-social explanations, significant intellectual progress might be expected in the fairly near future. In such research, the real interest will lie not in the quantification of the genetic or other biological components, ‘but rather in understanding how the risk is mediated and how [biological] factors combine with environmental influences to predispose to antisocial behaviour’ ( Sir Michael Rutter).

A. Bottoms

Bibliography

Brennan, P. A.,, Mednick, S. A.,, and and Volavka, J. (1995). Biomedical factors in crime. In Crime (ed. J. Q. Wilson and J. Petersilia).Institute for Contemporary Studies Press, San Francisco.
Ciba Foundation (1996). Genetics of criminal and antisocial behaviour. John Wiley and Sons, Chichester.
Raine, A., Brennan, P. A., Farrington, D. P., and Mednick, S. A. (ed.) (1997). Biosocial bases of violence. Plenum Press, New York.

See also degeneration.