Genetic factors Flashcards
The fact that concordance rates are not 100% suggests what?
There are environmental factors
What gene has been associated with aggressive behaviour?
MAOA
What is MAOA responsible for?
The metabolism of serotonin in the brain
What are low levels of serotonin associated with?
impulsive and aggressive behaviour
What was Brunner et al. (1997) research about?
- Studied 5 generations of a Dutch family
- Many male members demonstrated violent and aggressive behaviour (arson, rape etc)
- These men were found to have abnormally low levels of MAOA and a defect in the gene
Where is the MAOA-L most commonly found?
In populations where there has been a history of warfare
What does the MAOA-L gene show?
- MAOA-L gene = high serotonin levels = aggression
What are the issues regarding the research on MAOA gene?
- issues with reliability
- There is no consistent evidence as research suggests that all variations of the gene increase aggressive behaviours
A03 It is difficult to establish the genetic contributions to aggressive behaviour
- more than 1 gene usually contributes to a given behaviour
- there are many non genetic (i.e. environmental) influences on the manifestation of aggressive behaviour
- these influences may interact with each other
- genetic factors may effect which environmental factors may have an influence and vice-versa (gene-environment interaction)
A03 Many studies of aggression have relied on either parental reports or self reports of aggressive behaviour
- Whereas other studies have used observational techniques
- In the Miles and Carey meta analysis, reported on the facing page mode of aggressive behaviour in 24 studies analysed
- They found that genetic factors explained a large proportion of the variance in aggressive behaviour in studies that had used parental or self-reports.
- However, those that had used observational ratings showed a significantly less genetic contribution and a greater influence of environmental factors
- These inconsistencies in findings make it difficult to accurately assess the relative contributions of genetic and environmental factors in aggression
A03 Many studies in this area have focused exclusively on individuals convicted of violent crime.
- 2 difficulties arise when trying to draw meaningful conclusions from these studies
- The first problem lies with the ppts, convictions for violent crimes are relatively low compared to the vast numbers of violent attacks by individuals that never result in convictions
- They therefore represent just a small minority of those regularly in aggressive behaviours
- Secondly, offenders designated as ‘violent’ on the basis of court conviction are not necessarily the most serious
- a convicted murdered would be designated as violent despite perhaps having a lifetime free of crime
- This might explain why so many studies have found little or no evidence of heritability for violence
What is the difference between MZ twins and DZ twins?
MZ twins share 100% of their DNA, whereas DZ only share 50% of their DNA
Is there any research support for twin studies?
Caccaro found adult twin pairs, 50% of variance in direct aggressive behaviour towards others were attributed to genetic factors
What does it mean if a positive correlation is found in behaviour of adopted children and bio parents?
Suggests role of genetics
What if there is a positive correlation between adoptive children and foster children?
Suggests role of environment
