Biological explanations of offending

Genetics
1. Twin studies
  1. Compare concordance rates of MZ (identical) and DZ (non identical) twins.
    1. If the offending behavious is genetic expectd that there would be higher concordance rates for MZ than DZ twins
  2. Lange - found that concordance rates for DZ twins was 77% and for MZ twins was 12%.
    1. However Christiansens study was better controlled and he found that MZ twins had only 35% concordance rates and 12% for DZ,
  3. Early twin studies were not well controlled as there was no way to tell wether twins were MZ or DZ except to guess.
  4. Twins reared apart often attended the same schools and visited each other regularily.
2. Adoption studies
  1. Involve comparing the criminal futures of adopted children with their biological and adoptive parents.
    1. If there a greater degree of similarity between Biological parents and the children then criminality has a genetic basis
  2. Almost 50% of children in a sample of adopted children whose biological parent had a criminal record, themselves had a criminal record by the time they were 18. In a matched control group where mothers didn't have a criminal record, only 5% where convicted of criminal offences.
  3. Hutchings and Mednick- Found that if both Adoptive and biological parents had a criminal record, 32.6% of sons became criminals, if only adoptive father was a criminal 11.5% sons were criminal and if neither parents had a criminal record only 10.5% became criminals
  4. Children who are adopted tend to be placed in a similar enviroment to their biological parents
  5. Some children are adopted at a much later age so it may be early childhood experiences that cause criminal behaviour.
  6. Andrews and Bonta- Common criminality of biological parent and adopted child may be solely due to the effect of inherited emotional instability or mental illness rather than directly inherited criminality.
3. No single criminal gene has been found
4. Both twin and adoption studies seem to support genetic component but they do also indicate that the enviroment may also play a role as even MZ twins do not have 100% concordance.
Chromosones
1. Has been an attempt to link criminal behaviour to the possession of an extra Y chromosone
  1. Atypical chromosones
  2. The Y chromosone is responsible for male sexual development and testosterone which has been linked to aggression.
  3. In 1965, Jacobs et al claimed to discover the atypical chromsone pattern XYY in 1.5% of prison population as opposed to only 0.1% in normal population
    1. Within et al - found that only 12 out of 4500 had the extra Y chromosone and none had a criminal record.
      1. The XYY theory is no longer acceptable
They are both reductionist explanations attempting to reduce offending behaviour down to chemicals and cells

Next up

Biological explanations of offending

Description

Resource summary

Similar

	Created by issiscott12 almost 9 years ago