Genetic Factors in Aggression Flashcards
(15 cards)
what does the biological approach say about aggression
- aggression is determined by an individuals genetic makeup and is therefore inherited
- investigate this beleif by studying biologically related individuals who are simular in aggressive tendencies, whislt carefully seperating role of gentic and enviromental factors to establish cause
what do twin studies compare
- concordance rates between monozygotic and dizygotic twins
why do twin studies show aggression
- if MZ twins are more simular in their aggressive behaviour than DZ twins, then this could be attributed to their genetic make up rather than enviromental factors
- seeing as MZ twins share 100% gentic simularity and DZ share 50% genetic simularity
what do adoption studies involve
- investigating the likelihood of aggressive bahviour being displayed in adopted children who have aggressive bioloigcal parents but have not shared the same enviroment as them
- help to separate genetic and enviromental factors in aggression
why do adoption studies show aggression
- if a postive correlation is found between aggressive behaviour in adopted children and aggressive behaviour in their biological parents, a genetic component is implied
- if a postive correlation is found between the adoptee’s aggressive behaviour and the rearing family, then an enviromental component in implied
what is the other name for the MAOA gene
warrior gene
what is the MAOA gene responsible for
- breaks down and regualtes several transmitters that are involved in impulse control: seratonin, dopamine,, and noradrenaline
what abnormality of the gene do people inherit
- low activty version of the gene knwon as MAOA-L
what does the MAOA-L cause
- not enought enzyme MAOA is produced so levels are low
- low levels of this enzyme are not effectivley broken down and regulated after transmittion which stops effective communication between neurons in the brain
- results in an increased risk of aggression
how many males in the western population have the MAOA-L gene
1/3 males
stregnth: supporting ev twin
I: supporting evidence from twin studies for the role of genetic factors in aggression
E: McGue et al assesed aggression levles in 54 pairs of MZ twins and 97 pairs of DZ twins using the MPQ personality scale. in MZ twins there was aconcordance of 0.43 for aggressive behaviours, whereas DZ twins had a rate of 0.30
C: findings increase the validity of the genetic explanation, showing that the more genes shared with an aggressive individual, more likely we are to be aggressive
Weakness: methodological twin
I: methodological issues wirth twin studies
E: MZ twins share 100% of genes in common then we would expect concordance rates closer to 100% if aggression was entirley hereditary - not the case
higher concordance rates in MZ twins comapred to DZ could be explained in enviromental terms. - MZ twins enviroment to DZ as they are of same sex and identity more likely to be treated the same and have shared experiences
C:possible the enviromental explanation reduces the validity of the genetic explanation for aggression
strength: supporting adoption
I: evidence from adoption studies supports the role of genetic factors
E: Hutchings & Mendick carried out a meta analysis investigating aggression in 14,000 individuals who had been adopted in Denmark
found a positive correlation between the number of violent convictions committed to them by them and their biological father - even though they werent raised by them
C: increases the validity of the genetic explanation, showing that the more genes shared with an aggressive indiviudal, more likely we are to be aggressive
Strength: MAOA
I: supporting evidence for the role of the MAOA gene in aggression
E: brunner et al - 28 male members of a dutch family who were repeatedly involved in murder, rape, and physical assaults. they were found to have abnormally low levels o the enzyme MAOA in their brains, and have the low version of the gene
Sturart et al - 97 male offenders who had committed violence against partners. results showed that the males with the low activity version of the MAOA gene engaged in the highest level of violence and inflicted the most injuries on their partners
C: findings add to the validity of the genetic explanation, by showing a link between MAOA-L and aggression
weakness: gene enviro
I: gene-enivroment interactions that must be considered
E: Frazzetto et al - research has found an associations between high levels of antisocial behaviour and the MAOA-L in adult males, but only for those who had experienced a significant trauma during the first 15 years of life
those who had not experienced such childhood trauma did not have particularly high levels of aggression even though they possed the MAOA-L variant
C: enviromental influence reduces the validity of the genetic explanation for aggression, as it suggests that genes are not solely responsible
