AC2.1 Biological theories of crime Flashcards
What are monozygotic twins (MZs)?
These are identical twins, where single egg fertilised by single sperm, then splits in two
Mono means one
Zygote means egg
Share 100% of their DNA
What are dizygotic twins (DZs)?
Non-identical (fraternal) twins from 2 eggs
Separate eggs fertilised by separate sperm
Share only half their genes
Di means two
Zygote means egg
Share 50% of their DNA
What it concordance?
The level of relationship between two things
Explain the XYY theory regarding genetic theories
Suggests that some crime might be attributable to a chromosomal abnormality
XYY men are seen as more aggressive and more inclined to violent behaviour
Who suggested they men with XYY syndrome were more aggressive than normal XY men
Jacob er al. (1965)
Explain Lange’s (1929) findings of the twin study
Found that:
MZs showed a higher rate of concordance than DZs for criminal behaviour
10/13 MZs had both went to prison
2/17 DZs had such concordance
Explain adoption studies
The study looks at the impact of nurture in children who are raised by their non-biological parents
Explain what Hunchings and Mednick’s (1975) study on 14,000 adopted children found
Found that a higher rate of boys with criminal convictions had biological parents with criminal convictions
Suggesting that there is a link between aggression and genetics
What are physiological theories?
They focus on a person’s physical form as an indicator of criminality
What did Lombroso argue?
He argued that the criminal are a separate species.
A ‘born criminal’ could be determined by the physical shape of the head and face, people who commit crimes had atavistic features
Give some examples of atavistic features
Large or forward projection of the jaw High cheekbones Flattened or upturned nose Low sloping forehead Large ears
What did Lombroso examine
He examined the facial and cranial features of 383 dead criminals and 3839 living ones
Found that 40% of criminal acts could be accounted for by atavistic characteristics
What did Willian Sheldon propose?
Like Lombroso William proposed that criminal behaviour if linked to a persons physical appearance
What are the three somatotypes?
- Endomorph
- Ectomorph
- Mesomorph
Describe endomorph
(Fat and soft) tend to be sociable and relaxed
Describe ectomorph
(Thin and fragile) are introverted and restrained
Describe mesomorph
(Muscular and hard) are more aggressive and adventurous
What is a PET scan?
Used to scan and make detailed three-dimensional images of the inside of the body
Damage to the pre-frontal vortex of the brain can cause what?
May cause individuals to have an altered behaviour pattern
Being more immature and having an increased loss of self-control as well as having an inability to modify behaviour
What case study could be used to support the idea of brain abnormality?
Phineas Gage
Rod went through the left frontal lobe, associated with mental and emotional functions
His personality and behaviour was affected. He had bad language, anti-social, bad manners and became a liar
How does serotonin affect behaviour?
Some studies show that serotonin are linked to higher aggression
Serotonin controls a person’s mood
What did Scerbo and Raine’s meta-analysis show?
They conducted a meta-analysis on 29 studies into anti-social adults and children and found low levels of serotonin in all of them.
How can serotonin levels be controlled?
Through diet
In foods such as: dark chocolate fish, cheese, nuts, salmon, turkey and chicken
What is roid rage?
People who take large amounts of steroids and become extremely violent
What are the strength of twin studies?
- It is a natural experiment with the biological relationship between the twins being a natural occurring variable
- Christiansen (1977) supports criminality having a genetic component
- Results have helped in the prevention of vulnerable disorders
What are the limitations of twin studies?
- Lange (1929) were not controlled properly and lacked validity
Wasn’t clear if twins were MZs or DZs because the decision was based on looks - Small sample of twins, so cannot be generalised
- Of twins were brought up the same, criminality could be due to shared environment not genetics
