biological explanation-genetic and neural

• Genetic explanations focus on the heritability and role of candidate genes in development of criminal behaviour.
• Tiihonen et als study of 900 finish offenders revealed 2 abnormalities that may be associated with violent crime: the MAOA (L) gene- causing low levels of MAOA (controlling dop and serotonin) (LOW LEVELS OF SEROTONIN ASSOCIATED WITH AGGRESSION AND CRIMINAL BEHAVIOUR) and CDH13(linked to substance abuse and attention deficit disorder), individuals with this combination were 13 times more likely to have history of violent nature. 
• Genetic explanations can be supported through studying concordance rate of twin studies: Christiansen et al found concordance rates of 33% for MZ twins but only 12% concordance for non-identical DZ twins. Since MZ twins share 100% of their genetic information with each other, whereas DZ twins share only 50%, then this suggests that there is a moderate genetic or heritable basis of criminal behaviour. 
• Neural explanations highlight the role of the pre-frontal cortex, individuals who experience anti-social personality disorder show reduced activity in the PFC, part of the brain that regulates emotional behaviour. 
• . Raine found an 11% reduction in the volume of grey matter in the PFC of people with ADP compared to control groups.
• Mirror neurones: keysers found that only when criminals were asked to empathise with others did their empathy reactions activate. This is controlled by mirror neurons and suggests that criminals do experience empathy, although is not an automatic response.