Genes and Serotonin

Crime has been found to run in families, but this does not necessarily mean that nurture is responsible for crime. 

One biological explanation of crime is that some people may be predisposed to crime as they differ in terms of genes and serotonin levels. Low levels of serotonin have been associated with mood disorders and aggressive impulsive acts, as serotonin is involved in brain development, whilst some psychologists have claimed that inheriting certain genes or combinations may predispose someone to crime. 


Study: Brunner et al. conducted a case study of a Dutch family upon request of females in the family who were concerned about the behaviour of the males.

5 affected males were involved in the case study, all of whom were affected by borderline mental retardation and tendencies of abnormal violent behaviour including attempted rape and arson.  Urine samples were taken and analysed from the sample, from which Brunner et al found disturbed monoamine metabolism associated with a deficit of MAO A. A mutation in the X chromosome was also identified, which explained why no females were affected as the XX genetic make-up counteracted the mutation. 

MAO A is involved in serotonin metabolism, and thus Brunner et al concluded that the impairment of this gene was the cause of the mental retardation as well as their aggressive behaviour.