Genetic Flashcards
Genetic Explanations
The Likelihood of behaving in a particular way is determined by a persons genetic make up. IE Inherited from parents
Twin Studies for Genetic Explanation
If MZ twins are more alike compared to DZ Twins in terms of their aggressive behaviour then this should be due to genes rather than environment. Using comparisons of adult twin pairs it was found that nearly 50% of the variance in direct aggressive behaviour could be attributed to genetic explanations
Adoption Studies
If a positive correlation is found between aggressive behaviour in adopted children and aggressive behaviour in their biological parents, a genetic explanation rather an an environmental effect is implied. Its been found that a significant number of adopted boys with criminal convictions had biological parents with convictions for criminal violence, providing evidence for a genetic effect.
MAOA Gene
MAOA gene is an enzyme that among other things regulates the metabolism of serotonin in the brain. And low levels of serotonin are associated with aggressive behaviour.
A Study on a dutch family showed that many of the male members behaved in a particularly violent and aggressive manner. These men were found to have abnormally low levels of MAOM and a defect in the gene.
Evaluation: Problem In Sampling
Many studies in this area have focused exclusively on individuals convicted of violent crime. However, conviction for violent crime are few compared to the vast number of violent attacks by individuals that never result in a conviction. They therefore represent just a small minority of those regularly involved in aggressive behaviour. This means that it is difficult to draw meaningful conclusions from such studies.
Evaluation: Difficulties in determining the role of genetic factors
The connection between genetic factors and aggression is not straightforward because of problems determining what is and what is not a product of genetic inheritance.
For example it is difficult to establish genetic contributions to aggressive behaviour because more than one gene usually contributes to a given behaviour and there are many non-genetic influences on the manifestation of aggressive behaviour
Evaluation: Problem of assessing aggression
Many studies of aggression have used self-reports of aggressive behaviour, whereas other studies have made use of observational techniques. Studies using self-reports tend to show more genetic influences for aggression whereas observational ratings tend to show significantly less genetic contributions and a greater influence of environmental factors. Theses inconsistencies make it difficult to accurately assess the relative contributions of genetic and environmental factors in aggression.
Evaluation: Evidence for the influence of the MAOA gene
A Study of prisoners revealing that the MAOA low activity genotype in combination with another genes was associated with extremely violent behaviour. There was no substantial evidence for either of these genes among non-violent offenders. indicating that this combination of genes was specific for violent offending only.
Evaluation: MAOA explains gender differences
MAOA research can explain the uneven rates of violence for males and females.
The MAOA gene is linked to the X Chromosome. When men inherit an X-Linked abnormal gene they are more likely to be affected by it whereas women inheriting the same gene are generally unaffected as they have a second normal X Chromosome. This could explain why males typically show more aggressive behaviour than females.
