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Biological Theories, Twin Studies, Adoption Studies - Coggle Diagram
Biological Theories
Jacobs XYY Theory (1965)
This theory argues that crime is caused by a chromosomal abnormality.
These are in our cells and we have 46 of them. 44 of these determine things like the shape and constitution of our body, and the remaining two determine our sex.
In a woman, her two chromosomes are XX, and it is XY in a man
There is one condition called XYY (involving the presence of an additional Y chromosome)
XYY men are often called super males, they are thought to be more aggressive and more inclined to violence than other men with only 1 Y chromosome.They tend to be taller, well built, low intelligence and poor social skills
Jacobs (1965) Research has found that that XYY men are overrepresented in the prison population, with 15 XYY men per 1000 in prisons and 1 per 1,000 in the general population
There is real life application of this theory – both John Wayne Gacy and Richard Speck are said to have had an additional Y chromosome
Lombroso Theory
Lombroso's theory was that it was possible to spot a criminal by his physical features and argued that criminal behavior has a physical explanation
Lombroso’s starting point is that people are ‘born criminals’ and that crime can be explained biologically
He claimed that in earlier times, humans were uncivilized. They behaved like savages, e.g. aggressive and brutal and that offenders showed primitive characteristics and that they were a separate species with atavistic features
Atavistic features included large jaw, sloping forehead, high cheekbones, flat / upturned nose, large chin/ jaw, long arms, baldness, hard shifty eyes, tattoos and insensitive to pain
These criminals could not distinguish right from wrong, showed no guilt or remorse, were unable to form meaningful and loving relationships
According to Lombroso, females did not show these physical attributes, but were psychologically worse than male criminals
Lombroso sampled the proportions of almost 400 skulls of dead convicts and the heads of over 3,000 living ones. His key finding was that 40% of criminal acts were carried out by people who had atavistic features
Research conducted since Lombroso has failed to show any link between facial features and criminal behaviour
Not everybody with atavistic features is a criminal and not all criminals have atavistic features
Sheldon Theory
Sheldon argued that a person's body shape correlated to their personality, he put forward the idea that there were three body types.
Ectomorph = Thin and fragile; lacking both fat and muscle, self conscious, thoughtful, shy and introverted.
Mesomorph = Muscular and hard bodied, with very little fat and strong limbs; broad shoulders and a narrow waist, adventurous, domineering, enjoy physical activity and are more aggressive.
Endomorph = Rounded, soft and tending to be fat, lacking muscle or tone, with wide hips , sociable and relaxed, enjoy the company of others.
He used a sample of 200 photographs of college students and 200 photographs of male delinquents on a scale of 1 (not mesomorphic at all) to 7 (extremely mesomorphic)
The key finding was that those in the male delinquent group had a much higher score than those in the student group, thus making them more of a mesomorphic somatotype Suggesting that mesomorphic body types are more likely to be criminals
Twin theory/ Adoption Study
Twin Studies
Crime is biological, it runs in the family ( crime gene)
A zygote is a single cell that is formed when a sperm and egg fuse during fertilization, it contains all of the chromosomes (and so, all of the DNA)
Monozygotic (identical twins) share exactly the same DNA as they are both from the same fertilised egg
Dizygotic (non-identical twins) are from two separate eggs and share only 50% of their DNA
When both twins share a characteristic such as being aggressive, there is said to be a concordance rate
One of the earliest twin studies was reported from Lange (1929), The findings were that 10 out of 13 identical twins had served time in prison. 2 out of 17 non-identical twins had served time in prison.
Christiansen (1977) Studied 3,586 pairs of twins and found evidence to support the view as well with the following concordance rates:
Adoption Studies
The idea behind adoption studies is the comparison with criminals with both their biological and adoptive parents, These studies look at the impact of nurture (environment/upbringing) on children who are raised by their non-biological parent
Crowe (1972), compared groups of adopted children,
Biological mothers that Criminal records v Biological mothers that didn't have criminal records biological mother had a criminal record, 50% of the adopted children also had one by the time they were 18. In the other group only 5% of the adopted children had a criminal record by the time they were 18.
Hutchings and Mednick (1975) studied 14,000 adopted children and found that a high proportion of boys with criminal convictions had biological parents with criminal convictions as well.