Theories of Offending: The Genetic Explanation - Forensic Psychology

The genetic explanation:

A01:

Genetic explanations of offending propose that would-be criminals inherit gene(s) that predispose them to carry out criminal behaviour.

Twin and family studies seem to indicate that there may be a genetic factor to criminal behaviour. For example - Raine (1993) reviewed 13 studies and found that the concordance rate of offending behaviour was 52% for MZ twins and 21% for DZ twins.

Grove et al (1990) investigated concordance rates for criminal behaviour in 31 sets of MZ twins, who had been reared apart shortly after birth. They interviewed these twins individually using the double-blind technique, and the interviewer scored the individual for alcohol problems, drug problems and child/adult antisocial behaviour. The drug score, and both anti-social scores showed significant heritability – with concordance rates for antisocial personality at 29%.
This illustrates that these traits have a substantial genetic component and therefore provides strong support for this theory.

A03:

This study by Grove et al (1990) has both strengths and weaknesses. For example, it relied on interviews and therefore the validity must always be questioned as bias can be a major limitation – eg. if the interviewee lies, or if they give answers they perceive to be socially desirable. However, this was a very controlled study, as it used a double-blind technique and therefore any potential researcher bias was eliminated which, consequently, increases the validity.

Lange (1929) carried out one of the earliest twin studies of criminality and found concordance rates of 77% for MZ twins and 12% for DZ twins. This suggests that criminality may be genetic, since MZ twins share 100% of their genes, and their concordance rates are significantly higher – this therefore supports the genetic explanation.

However, the concordance rates still aren’t 100% and therefore criminality cannot be wholly genetic, and there must be other factors involved that aren’t considered. Additionally, early twin studies neglect the fact that most twins with share the same environments, and this therefore is a confounding variable – so how do we know whether its nature or nurture that is affecting such criminality?

A strength of this genetic explanation is that there are supporting adoption studies. For example, Crowe (1972) found that almost 50% of adopted children, whose biological mothers had a criminal record, had a criminal record themselves by the age of 18. This provides strong support for a genetic link of criminality, as they had different environments which minimises the influence of nurture. However, maybe the stress of adoption led to criminal acts, rather than the genetics and therefore the validity must be questioned.