AC 2.1 Describe biological theories of criminality Flashcards
What are the genetic theories?
- XYY theory
- Twin studies
- Adoption studies
What is the XYY theory?
The theory suggest that some crime might be an attributable to a chromosomal abnormality. XXY men (sometimes called super males) have been of interest to criminologists because of the suggestion that they are more aggressive. Jacob et al. (1965) suggested that men with XYY syndrome were more aggressive than normal ‘XY’ men. There are also some studies that suggest that XYY men are over-represented in a prison population. There are 15 suffers per 1,000 people in prison whereas there are 1 per 1,000 people in the general population.
What are twin studies?
Identical twins are monozygotic (MZ) as they are from one fertilised egg. Such twins share 100% of their DNA. Dizygotic (DZ) twins come from two separate eggs and share 50% of their DNA.
One of the earliest twin studies was reported by the German physician Johannes Lange (1929). He found that (MZ) twins showed much higher degree of concordance than DZ twins for criminal behaviour. 10 of the 13 MZ twins had both served time in prison whereas only 2 of 17 DZ twins had served time in prison.
What are adoption studies?
Studies look at the impact of nurture on children who are raised by their non-biological parents. If the child is more similar to their biological parents than their adoptive parent, with whom they share the same environment, a genetic bias of criminality may be suggested. On the other hand, if a child is more similar to their adoptive parents an environmental argument for criminality is preferred.
Hutchings and Mednick (1975) studied 14,000 adopted children and found that a high proportion of boys with a criminal record had biological parents with a criminal record too.
What are the psychological theories?
- Lombroso’s theory
- Sheldon’s theory
- Brain abnormalities
What was Lombroso’s theory?
He believed that the criminal is a separate species, a species that is between a modern and primitive humans. He also argued that a ‘born criminal’ could be determined by the physical shape of the head and face.
Examples of atavistic features include;
-High cheekbones
-Flattened or upturned nose
-Low, sloping forehead
-Large ears
Lombroso examined the facial and crainial features of 383 dead criminals and 3,839 living criminals and concluded that 40% of criminal acts could br accounted for by atavistic features.
What was Sheldon’s theory?
Sheldon (1949) believed that criminal behaviour is linked to a person physical form.
Sheldon believed that there was the body types;
- Endomorphic (fat and soft) tend to be sociable and relaxed
-Ectomorphic (thin and fragile) are introverted and restrained
-Mesomorphic (muscular and hard) are more aggressive and adventurous
Sheldon found that many criminals prone to committing violence and aggressive acts were mesomorphic and the least likely were ectomorphic
What are brain abnormalities?
Several research studies have suggested that damage to the pre-frontal cortex may cause an individual to have an altered behaviour pattern. Becoming more immature and having an increased loss of self-control as well as having an inability to modify behaviour.
