The Emergence of Violent Behaviour: An Examination of Individual and Social Factors: Genetics and Criminal Behaviour

Genetics and Criminal Behaviour: Twin Studies

The principal methodology used to study the relationship between genetics and criminality has typically been longitudinal family studies, which examine the concordance rates for criminal behaviour between monozygotic (MZ) and dizygotic (DZ) twins; that is, how frequently both twins are involved in criminal behaviour.

MZ twins are known as identical twins and DZ twins are non identical twins.

While the former (MZ) develop from the splitting of a single egg and share almost 100% of the same genes, fraternal twins (DZ) share 50% like ordinary siblings. Thus when DZ twins share the same environment any significant differences recorded between them are likely to be due to genetics.

This provides a unique opportunity to explore genetics and criminal behaviour.

Whilst many of these studies have indicated support for a genetic component to criminality (Bartol, 1999 recorded an average concordance rate for criminal…