Evaluation

• Evidence supporting Genetic explanations - Diathesis stress model

  Mednick (1984) - 13,000 Danish adoptees study

  Researchers defined criminal behaviour as being in possession of at least one court conviction and this was checked against Danish police records for each of the adoptees

  When neither the biological nor adoptive parents had convictions, the percentage of adoptees that did was 13.5%

  This figure rose to 20% when either of the biological parents had convictions and 24.5% when both adopted and biological parents had convictions

  Environmental influence cannot be disregarded
• Evidence supporting genetic explanations - Problems with twin studies

  Early twin studies (Lange) were poorly controlled and judgement related to zygosity (MZ or DZ) were based on appearance rather than DNA testing - resulting in them lacking validity

  Typically involved smaller sample sizes, furthermore twins are an unusual sample in themselves and may not represent the rest of the population

  FInally, the fact that most twins are reared in the same environment is a major confounding variable as concordance rates may be due to shared learning experience rather than genetics
• Evidence supporting neural explanations - Raine

  Mass of well-controlled evidence (control groups and matched pairs)

  However, still correlation though - no use of true experiments
• Evidence supporting neural explanations

  May be treatment implications - case of Michael Oft

  A former prison officer and teacher from Virginia whose behaviour started to change in 2000 - developed paedophilic tendencies

  It emerged he had a brain tumour, which was then removed and his behaviour returned to normal (Raine 2014)

  Cause of effect - changes in brain function may be a result, rather than cause of behaviour (risk-taking)

  How valid and reliable are FMRI and PET?
• Reductionism and/or determinism 


  Criminality is complex - explanations that reduce offending behaviour to a genetic or neural level may be inappropriate and overly simplistic

  Crime does appear to run in families, so does emotional instability, mental disorders, social deprivation and poverty (Katz et al 2007)

  Makes it difficult to disentangle the effects of genes and neural influences from other possible factors
• Reductionism and/or determinism 


  In the field of criminality, the notion of ‘criminal gene’ creates a problem as the legal system is based on the premise that criminals have personal and moral responsibilities for their crimes, and only in extreme cases, such as a diagnosis of mental disorders, can someone claim they were not acting under their own free will?