genetix explanation

• we inherit 50% of our genetic material from our mother and 50% from our father
• a tendency for criminal behaviour may be genetically inherited from our parents
• to investigate the inheritability of offending behaviour, twin studies are conducted where concordance rates between MZ twins and DZ twins are compared
• MZ twins share 100% of genes
• DZ twins share 50% of genes
• Christiansen studied 3586 twin pairs in Denmark and found that concordance rates for offending of

  • 35% MZ male 21% MZ female
  • 13% DZ male 8% DZ female
• however twin studies are criticised because MZ twins may share more similar environments than DZ twins

  • e.g. MZ will look more similar to each other than DZ twins and this will impact the way they're treated.

  therefore the higher concordance rates in MZ twins could be explained by environmental factors, reducing the support given for the genetic explanation given by the twin studies
• adoption studies are considered as useful as they are better at disentangling the environmental influences from the genetic influences than the twin studies
• adoption studies involve comparing the child with their biological parents and their adoptive parents
• Mednick et al 1987 studied 14,000 adoptees and found that 15% of boys adopted by a criminal family went on to offend, compared to 20% of those whose biological family were criminal
• adoption studies are criticised as environmental factors are not fully ruled out

  • children are not always taken from their biological parents straight after birth. According to psychologists such as Freud and Bowlby even very early experiences can have a powerful influence on development. This may reduce the level of support given for the genetic explanation by adoption studies