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Biological Explanations - Coggle Diagram
Biological Explanations
Atavistic Form
The historical approach to offending - An early biological explanation which proposed that criminals are a subspecies of genetic throwbacks that cannot conform to the rules of modern society. Such individuals are distinguishable by particular facial and cranial characteristics.
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Genetic Explanations
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Twin Studies
Christiansen (1977) sample of 87 MZ and 147 DZ twins. 33% concordance rate of offending in MZ twins. 12% in DZ twins.
Johannes Lange (1930) investigated 13 MZ twins and 17 DZ twins - found that 10 of the 13 MZ twins had both served time in prison. Only 2 of the 17 DZ twins had both served time in prison.
Gene abnormalities
The low activity form of the MAOA gene has been linked to increased levels of aggression and violence.
Tilhonen et al (2014) found that mutations on the MAOA gene have been linked to aggressive behaviour.
The cell-cell signalling gene CDH13 is associated with a wide spectrum of neuropsychiatric disorders, including ADHD, addiction, and major depression. CDH13 regulates axonal outgrowth and synapse formation, supporting its relevance for neurodevelopmental processes.
Adoption Studies
Mednick (1984) 13,000 adoptees studied in Denmark - 13.5% of adopted children had criminal record where both biological and adopted parents had no convictions.
Increased to 20% when biological parents had convictions.
Increased to 24.5% when adopted parents and biological parents had convictions.
Neural Correlates
Much of the research is on Antisocial Personality Disorder (APD) - people with this show a reduced emotional response and lack of empathy for others.
Raine (2000) research shows brain scans with reduced activity in the prefrontal cortex - the part of the brain responsible for emotions and scans show 11% reduction of grey matter.
In the 1990s neuroscientists identified cells in the premotor cortex of monkeys that had an unusual response pattern. They were activated when the monkeys performed a given action and, mirror-like, when they saw another individual perform that same movement.
Keysers et al (2011) found APD individuals could activate mirror neurons if asked to empathise but under normal situations they seemed "switched off".