genetic factors in aggression Flashcards
what is meant by genetic factors
the likelihood of behaving in a certain way is determined by a persons genetic make-up inherited from parents
list the different ways genetic factors can be explored
1) twin studies
2) adoption studies
outline how twin studies can be used t o research genetics in aggression
1) identical twins share 100% of their DNA vs non-identical twins which only share 50%
researchers can compare the degree of similarity for a particular trait, such as aggression between sets of identical twins and compare this to the sets of non-identical twins
therefore both twins share the same enviornment but are different in regards to gentic similarity so it can be concluded any differences are due to genetics
outline a study into aggression using twins
berkowitz
- found a 87% concordance rate in identical twins vs 72% in non-identical twins when measured for aggressive and anti-social behaviour
outline how adoption studies can be used to investigate genetic factors in aggression
- can be used to separate the role of environmental and hereditary aggression
- if a positive correlation is found in aggressive behaviour in an adopted child and biological parents a genetic effect is imp0lied
- if a positive correlation between adoptees aggressive behaviour and the rearing fam8ily then an environmental effect is implied
outline a study into aggression using adoption
a meta-analysis combined of 51 twin and adoption studies concluded that aggressive anti-social behaviour was largely a product of genetic influences.
however they found a range of factors such as age and assessment for aggression effected the effect of genetic so suggest that whilst genes play a role in aggressive behaviours the influence of other factors effects how these behaviours are displayed
outline Hutchings and Mednicks research into adopted children and aggression
a study of over 14000 adoptions in Denmark found that a significant number of adopted boys with criminal convictions had biological parents with convictions for criminal violence
what is MAOA
the MAOA gene regulates the enzyme MAOA which breaks down neurotransmitters serotonin and dopamine
monoamine oxidase A
outline how the MAOA gene is linked to aggression
variations in the MAOA gene regulates how much MAOA is produced
the variation, MAOA-L shows low level production of MAOA therefore there is less break down of serotonin so there is increased serotonin activity in the brain associated with aggression and increased susceptibility to impulsive behaviour
outline a study exploring the MAOA gene
Mcdermott et al
found that MAOA-L pps displayed higher levels of aggression, measured by forcing a fictional pps to eat unpleasantly hot and spicy sauce, when provoked compared to MAOA-H
why might the diathesis stress model be applied to the MAOA gene and provide a study to support it
it is found in 1/3 of western men and 60% of some communities, however, not all of these individuals are aggressive, suggesting other factors must play a role in the activation of this gene= the gene provides a venerability but the environment influences if it is expressed
supported by Caspi et al- found that those with the MAOA-L gene were significantly more likely to grow up with antisocial behaviour but only if they had been maltreated as a child
evaluate genetic factors in aggression
1) research support= a study in Finland looked at Finnish prisoners revealing that the MAOA-L activity gene in combination with another gene CDH13 was associated with extreme violent behaviours, there was no evidence for either of these genes among non-violent offenders
2) issue and debate= nature vs nurture- role of nature ignores role of environment- maybe interactionist approach better suited
3) real world application= explains gender differences in aggressive behaviour- MAOA gene is linked to the X chromosome, females have two X chromosomes where as men only have one. If men inherit a recessive MAOA-L gene it will be shown in the phenotype no matter what, increasing their aggression, compared to women where one X has the normal gene nd the other recessive therefore the recessive is not expressed
4) research methods- problems of sampling = many studies focus only on individuals convicted of violent crimes. Those convicted of violent crimes are relatively few when compared to the number of violent attacks by individuals which never result in a conviction, therefore they don’t represent the entire population decreasing ecological validity
