biological theories of criminality Flashcards
1
Q
what are the three types of biological theories?
A
genetic theories
physiological theories
brain abnormalities
2
Q
what are chromosomes?
A
the pattern of chromosomes determines a persons sex, contain our genes
female = XX male = XY
3
Q
what is the XYY theory?
A
- jacobs suggested that a presence of an extra Y chromosome in males has been linked to crime
- typically more violent and aggressive than normal XY men
- studies suggested that XYY men are over-represented in prison in comparison to the general population
4
Q
case study for XYY theory
A
John Wayne Gacy
- serial killer, had XYY syndrome
- sexually assaulted, tortured, and killed at least 33 men in the USA
- nicknamed the ‘Killer Clown’
5
Q
what are twin studies?
A
- allow researchers to compare genetic and environmental influence
- identical twins are monozygotic, sharing 100% of DNA due to being fertilised in one egg
non-identical are dizygotic, sharing 50% of DNA due to being fertilised in two eggs - if they share the same characteristic, there is said to be a concordance rate
- higher concordance with mz twins compared to dz twins suggests genetics play a role
6
Q
Christiansen’ study
A
- 3586 twin pairs in Denmark
- where one identical twin had a conviction, there was a 52% chance of the other twin also having a conviction
7
Q
adoption studies
A
- adopted child shares the same env as adoptive parents however shares the same genes as their biological parents
- if criminal behaviour similar to birth parents, suggests genetic explanation
8
Q
Mednick et al
A
- examined data on 14,000 adopted sons in Denmark from 1924-47
- sons are more likely to have a criminal record if the birth parent did
- only 14.7% had a criminal record if an adoptive parent had one
- suggests genetic explanation
9
Q
Lombroso’s theory
A
- criminals were physically different, born criminal and a seperate species, criminality heritable
- criminals were atavistic, throwbacks to a primitive stage of evolution
- identified by physical features, such as prominent eyebrow arches, large eye sockets, large arms, high cheekbones, large ears
10
Q
modern study of lombroso
A
- study in China with 1856 Chinese men
- 50 % had conviction, entered into AI programme
- wrongly flagged innocent men 6% of the time but correctly identified 83% of the real criminals
11
Q
what is Sheldon’s somatotypes theory?
A
- criminals as physically different, in terms of body shape
- endomorphs, ectomorphs, mesomorphs
12
Q
endomorph body type
A
- lack muscle and fat
- round
- wide hips
- sociable, relaxed, comfortable
13
Q
ectomorph body type
A
- thin and fragile
- flat-chested
- thin face
- self-conscious, fragile, thoughtful
- least likely to commit crime
14
Q
mesomorph body type
A
- muscular and hard bodied
- broad shoulders
- narrow waist
- adventurous, assertive, domineering
- high pain tolerance, ruthless
- most likely to commit crime
15
Q
sheldon’s study
A
- used a sample of photographs of college students and delinquents
- rated 1 to 7 on resemblance to mesomorphs
- delinquents had higher average than college students (4.6 compared to 3.8)
16
Q
brain abnormalities
A
- damage and reduced activity in the pre-frontal cortex may cause individuals to have altered behaviour pattern
- become more immature and lose self-control
17
Q
brain abnormalities - Raine
A
- studied PET scans of the brains of impulsive killers
- damage was found in the pre-frontal cortex
- part of the brain that controls impulsive behaviour
- also found abnormalities in the limbic system including the amyglada and thalamus
