Description of Genes

• Introduction:

  • Research on twins suggest that genes play a role in CB.
  • Much higher rate for both twins when they are identical compared to non-identical. (Concordance rate)
  • Genetic argument proposes that more than one gene can predispose individuals to CB. (Polygenic explanation)
• MAOA Gene:

  • Found on the X Chromosome and nicknamed the 'warrior gene'
  • Responsible for producing the MAOA enzyme which breaks down excess serotonin that stays in the synapse.
  • Defective MAOA gene (MAOA-L) develops if the person is exposed to too much serotonin in utero development.
  • The brain becomes insensitive to serotonin in later life = irregulated moods and possible criminal behaviour.
• CDH13 Gene:

  • Involved in communication between brain cells and linked to the control of impulsive behaviour.
  • Defective CDH13 is often found alongside a defective MAOA gene.