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Question 1

Describe Jacobs xyy study in relation to genetic theories of criminality

Answer 1

• This theory suggests that criminality can be attributed to a chromosomal abnormality.
• Chromosomes are structures in cell nuclei that contain our genes. Usually, each person has 46 chromosomes. Sex is determined by the pattern of the person’s sex chromosomes: XX in a woman and XY in a man. There is a genetic condition in which a male has an extra male (Y) chromosome, giving a total of 47 chromosomes. Such a condition occurs in 1 in 1,000 male births.
• Jacobs et al (1965) suggested that men with the XYY syndrome were more aggressive than normal ‘XY’ men. XYY men are over-represented in the prison population with 15 per 1,000 in the male prison population.
• The study from Jacob et al was based on studies of imprisoned criminals, such as those in secure hospitals, where a higher-than-average proportion of inmates were found to have XYY syndrome. Many had histories of aggression and violent assault. Price and Whatmore alleged that XYY males tend to be immature and unstable with a tendency to commit motiveless property crimes.

Question 2

Describe adoption studies in relation to genetic theories of criminality

Answer 2

• The underlying principle of such studies in explaining criminal behaviour is the comparison of criminals with both their biological and adoptive parents. If, in criminal behaviour, the child is more similar to their biological parents than to their adoptive parents, with whom they share the same environment, a genetic basis of criminality may be suggested.
• Mednick et al (1987) looked at court convictions in a small European country and found 14,000 adoptees amongst them. The criminal records of their biological and adoptive parents were then investigated. Many of the adoptees had biological parents who were criminals (and there was a particularly strong relationship for sons and fathers).

Question 3

Describe twin studies in relation to genetic theories of criminality

Answer 3

• Such studies support the contention that a heritable trait may increase the risk of criminal behaviour. Identical twins are from one egg and known as monozygotic (MZ) and share 100% of their DNA. Dizygotic (DZ) twins are non-identical and are from two separate eggs. They share 50% of their DNA.
• Where twins share characteristics or act in a similar way, this is said to be a concordance rate. Twin studies have taken place and there is evidence to suggest genetics or nature may play a role in criminality.
• The concordance rate as regards criminality is greater with MZ twins. A 1929 study of 30 pairs of twins by the German physician Johannes Lang found that while 10 of the 13 MZ twins studied had served time in prison, the concordance rate for DZ twins was 2 of the 17 twins studied. Research by Christiansen (1977) found that criminality concordance rates for MZ twins was 35% and for DZ twins it was 13%.

Question 4

Describe Lombrossos theory in relation to physiological theories of crime

Answer 4

• This theory suggests that the criminal is a separate species, a species that is between modern man and primitive humans.
• In 1876 Lombroso argued that criminals were physically different from non-criminals. He measured and recorded details of the heads and faces of thousands of prisoners. He argued the physical shape of the head and face determined the “born criminal”. He claimed that criminality was heritable.
• He identified key physical characteristics of a criminal. These included: Such features include low sloping foreheads, large jaws, or forward projection of jaw, receding chin, twisted nose, long arms relative to lower limbs, excessive cheekbones, large ears and excessive wrinkles
• Criminals have ‘atavistic’ (i.e., primitive) features, which are ‘throwbacks’ or characteristics from an earlier stage of human development. He argued that criminals were pre-social, unable to control impulses and had a reduced sensitivity. They manifest as a tendency to commit crimes. Lombroso’s view criminals could be easily identified, marking them out as different to ‘normal’ citizens.

Question 5

Describe sheldons theory in relation to physiological theories of crime

Answer 5

• A somatotype refers to a person’s body type/shape. William Sheldon believed that certain somatotypes are more likely to commit crimes than others.
• He identified three main somatotypes.
• Endomorphs are fat and soft, lacking muscle tone. Their personality is relaxed and socially outgoing.
• Ectomorphs are thin and fragile. Their personality is introverted and emotionally restrained.
• Mesomorphs are muscular and hard bodied, with very little fat and are strong. Their personality is adventurous and aggressive.
• Sheldon, using a correlation study of 4000 inmates, found that many convicts were mesomorphic and they were least likely to be ectomorphic
• He therefore argued that mesomorphs are more likely to engage in criminal activity. He claimed they would be attracted to the risky nature of crime and their physical advantage would be an asset when conducting crimes. They also have a high pain threshold and are more likely to be callous and ruthless.