2.1 (biological theories) Flashcards by Katie Acred

what are the biological theories?

• Jacob’s XYY
• Candidate genes
• Twin studies
• Adoption studies

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what does XYY theory suggest?

that criminality may be attributional to a chromosome abnormality

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how many chromosomes has someone got?

46 chromosomes
• 44 for physical form
• 2 to determine sex

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what chromosomes for male and female have?

XY (male)
XX (female)

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what is a super males?

XYY (47 chromosomes)
• likely to be more aggressive and violent
• why: higher levels of test prone (extra Y)
• they are very tall, well built and have low intelligence

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how does a super male explain criminality?

• violent crime (testosterone)
• lack of understanding of consequences/logic
• psychological characteristics- easy to commit crime

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what is Jacob’s study?

• studied imprisonment criminals, such as those in securepsychiatric hospital’s
• higher proportion of inmates tended to have XYY syndrome
• 15/1000 prison
• 1/1000 general population

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why is there a higher population of XYY in prison?

• more aggressive- criminal
• low intelligence- like to get caught
• stereotypical- self fulfilling prophecy

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what is example of someone with an XYY gene?

• 1968, Margaret Burke was raped murdered in New York City but 6”8 man with XYY and anti-social behaviour
• the defence was the deviance chromosome structure caused psychiatric difficulty made the defendant incapable of the men’s rea
• this attempts to prove a genetic theory of sanity failed and Farley was convicted

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what are the 3 strengths of the XYY research?

1) consistent with Shedon’s theory
- mesomorphic and criminality
2) Jacob’s
- found an association between XY criminals and aggression
3) Price and Whatmore
- found links between XYY and property crjme

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what are the 5 limitations of XYY research?

1) XYY may fit the stereotype of violent offenders and so are labelled by the courts as criminals rather than committing crimes
2) Rare condition (15/1000 in prison and 1/1000 in general population)
- cannot explain all criminality, other factors must play a role
3) suggest only males can be criminals, however, many females also commit crime (20% or criminals are female- XYY cannot explain that)
4) Only suggests a correlation cannot establish XXY causes violence and crime
5) Jacob’s research only looked at imprisonment criminals, not all criminals
- XYY may just be more likely to get caught

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what are the candidate genes?

• MAOA
• CDH- 13

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what is MAOA?

• this linked to increased levels of violences
• lack emotions from harming others
• controls dopamine and serotonin
• characterised by intellectual disability and behaviour problems

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what is the study for MAOA?

Brenner et al (1993)
• analysed the DNA of 28 male members of a Dutch family with a history of impulsive and violent criminal behaviour
• found they showed a particular gene that lead to low levels of monoamine oxidase A (MAOA)

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what is CDH-13?

• identified as a ADHD gene which is associated with violent criminality
• linked with substance abuse and attention deficit disorder

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what was the study of CDH-13?

Tihoen studied 900 offenders and found abnormality on 2 genes associated with violent crime

what is the concordance rates for twin studies?

the rate of probability that two people with shared genes will both develop offending behaviour

what is the2 types of genes in twins?

1) Mz (monozygotic
2) Dz (dizygotic)

what is the dizygotic and monozygotic gene?

Dz:
- Non identical
Mz:
- Identical
- Genetic element (inherited a candidate gene)
- Mz share more DNA and have concordance rate of rate of criminality
- Genetic risk

how is the DNA shared with Mz or Dz?

Mz- 100%
Dz- 50%

what did LANGE study conclude of Mz and Dz?

Mz: 10/13 also had a twin in prison
Dz: 2/17 also has a twin in prison

what did CHRISTIANISEN (1977) study conclude of Mz and Dz?

87Mz and 147Dz

Mz: 35% both in prison
Dz: 13% both in prison

what did Raine (1993) Delinquent Teens?

Mz: 52% both in prison
Dz: 12% both in prison

what is 2 strengths of twin studies?

1) consistent evidence that there is a relationship between genes and criminality
2) concordance rates for Mz are higher
- suggests a genetic element

what is the 4 weakness of twin studies?

1) biological determinism - assumes individual have no free will/ control over criminals behaviour but are products of their genes - contradicts the CJS 2) however, ignores the role of the environment which may also play a role in offending and may explain why concordance rated for Mz- twins are not higher (not 100%) 3) twins also have showed environment, which could also explain higher concordance rates - it is very different to separate genes from environment when looking at twins 4) lack of control in some twin studies- LANGE’s research was based on appearance to determine Mz/Dz rather than DNA

who researched adoptive studies?

Mednick

what was Mednick’s first research on Adoption studies?

1975 • 14000 adopted children • high proportion of boys with criminals convictions also had criminals biological parents (genetics)

what was Mednicks 1994 study?

• no relationship between criminal convictions and adoptive parents • this is better than twin study as this allows as to separate nature and nurture

what is the 2 strength of adoption studies?

1) adoption studies allows researchers to separate nature and nurture and see which has the bigger influence 2) Mednicks research supports that genetics play a role in criminal behaviour- stronger correlation with biological parents than adoptive parents

what is the 3 limitations of adoptive studies?

1) age of adoption could have an influence on criminal behaviour- if adopted later would have been influenced by biological parents environment 2) research is correlational- doesn’t allow us to establish if genes have caused criminal behaviour 3) adoption process may not be random- children may be placed in similar environments to their biological parents