biological explanations

• Biological explanations explain criminality as a result of our biological systems, such as our brain and nervous system, genes, and hormones.
• Early theories believed that criminals had certain body shapes and facial characteristics that indicated whether they were a criminal and what type of crime they would ave been likely to commit.
• Studies have found that criminality runs in families.

  • However, such evidence is undermined by the possibility that upbringing might account for these findings or that a social factor, such as poverty, may explain the tendency for criminality to run in families.
• More reliable evidence has been found using twin studies.

  • If identical twins (monozygotic) are both more likely to become criminals compared to non-identical twins (dizygotic), then there could be some evidence that criminality has a genetic basis.
• Karl Christiansen (1977) found that:

  • 35% of identical male twins recorded in Denmark were both criminals compared to 13% of non-identical male twins.

  For female twins,

  • 21% of identical twins were both criminals and 8% of non-identical twins.
• Karl Christiansen (1997):

  Identical twins are likely to be raised in a more similar way than non-identical twins (who may be of a different sex).

  • This shared upbringing could explain the slightly higher percentage of identical twins who are both criminals compared to non-identical twins.
• One way to rule out the potential of upbringing is to use evidence from adoption studies. Here, the biological parents and adoptive parents are compared to the child in terms of whether they have criminal records.

  • If the child is adopted at an early age, we can then assume that any similarity between the biological parent and child is inherited.
• Barry Hutchings and Sarnoff Mednick (1975):

  • Found that 21% of adopted children who went on to commit a crime had a biological father who was convicted of a crime.

  This compared to 10% of children whose biological father was not convicted of a criminal offence but the adoptive father had a criminal record.