Jacobs et al
- Created by: ashfarmer3
- Created on: 06-02-23 09:08
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- XYY Theory
- Facts
- Jacobs is a Scottish geneticist
- She was the first to describe discovery of abnormal chromosome in humans.
- Born: 8 October 1934.
- 1.Claims
- Men with XYY syndrome were more aggressive than 'XY' men.
- This abnormality is the presence of an extra Y chromosome.
- XYY men=supermale.
- Supermales more inclined to be violent.
- 2.Components
- Correlational study comparing men in prison to general population- seeing how prevalent XYY was.
- 15 sufferers per 1000 in prisons and 1 per 1000 in general society.
- Prevalence of XYY men in prison was 25-60x as high then general society.
- Early assumptions- XYY made men more aggressive and below-average intelligence.
- Accepted symptoms now- more physically active, tendency to be more impulsive.
- Correlational study comparing men in prison to general population- seeing how prevalent XYY was.
- 3.Credibility
- Scientific status
- Been studied by other geneticists for 40-50 years.
- Reductionist- reduces criminal behaviour down to one explanation.
- Deterministic- implies that males with extra Y chromosome inevitably are more aggressive than males without it.
- This theory doesn't attempt to explain why women commit crime.
- Richard Speck-known alcoholic.
- Killed 8 people, could be due to alcohol not XYY chromosome.
- 4.Analysis
- John Wayne Gacy
- Has XYY syndrome.
- Sexually assaulted 33 men in USA.
- Could be due to the XYY chromosome.
- Richard Speck
- Sid to have XYY chromosome.
- Known for killing 8 student nurses.
- Was an alcoholic so murder could've been down to this.
- John Wayne Gacy
- Untitled
- 5.Refuting Evidence
- Focuses too much on genetics ignoring environmental triggers.
- Richard speck- degenerate alcoholic.
- Theilgaard- took blood samples from 30,000 criminals.
- Found characteristics of aggression not linked to XYY men.
- Focuses too much on genetics ignoring environmental triggers.
- 6.Supporting Evidence
- Nature Genetics published discovery.
- Supporting idea that a chromosomal addition was possible.
- American Journal of Medical Genetics
- compared XYY males with XY siblings and found XYY sibling scored lower on intelligence tests.
- However, no link between low intelligence and criminal behaviour.
- compared XYY males with XY siblings and found XYY sibling scored lower on intelligence tests.
- Nature Genetics published discovery.
- Facts
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