Aggression - Genetics Flashcards
What are four AO1 factors which you should look at in genetics
Twin studies
Adoption studies
Research on genetics factors
MAOA gene
Explain twin studies as a genetic factoring a study
Coccaro et al 1997 - found that nearly 50% of the variance in direct aggressive behaviour could be attributed to genetic factors
What type of twins are identical
Monozygotic
What type of twins are non-identical
Dizygotic (50%)
Explain adoption studies
untangle relative contributions of environment and hereditary in aggression
What happens if the correlation positive is in in adoptive children and their biological parents
if the correlation is positive between aggressive behaviour and biological parents then genetic factor is applied
What happens if the correlation is positive between adoptees aggressive behaviour and their rearing family
then an environmental factor is applied
explain an adoption study
14,000 adoption in Denmark found that a significant number of adopted boys with criminal convictions had biological parents with criminal convections providing evidence for the genetic effect
Give a 1997 study on genetic factors in aggression
Miles and Carey
Explain a 1997 study on genetic factors in aggression
meta analysis of 24 twin and adoption studies that showed a genetic basis.
The results suggest a strong genetic factor that could account for as much as 50% of the variance in aggression
who did this - meta analysis of 24 twin and adoption studies that showed a genetic basis.
The results suggest a strong genetic factor that could account for as much as 50% of the variance in aggression
Miles and Carey 1997
What was another important factor in in Miles and Carey 1997 study
Age as with both genes and environment being influential in determining aggression in youth but at later ages it way mainly the influence of genes that determined aggression
What is another study on genetic factors in 2002
Rhee and Waldman
What did Rhee and Waldman do?
combined the results of 51 twin and adoptions studies finding that aggressive behaviour was largely due to genetics
Counter argument for Rhee and Waldman
the same as Miles and Carey other factors such as age suggest that other factors effect the expression of aggressive behaviour
What is MAOA
Monoamine oxidase is an enzyme that among other things regulates the metabolism of serotonin in the brain
What is the role of MAOA
regulates the metabolism of serotonin in the brained low levels are associate with impulsive behaviour
explain a study on the role of MAOA
A 1980S study on a dutch family found males behaved aggressively and a majority had been involved in serious crimes of violence these males were found to have abnormally low levels of MAOA in their bodies and a defect in this gene was later identified
Explain MAOA-H + MAOA-L using a study
Caspi et al 2002 on 500 male kids they discovered a variant of the gene associated with high levels of MAOA-H and a variant associated with low levels of MAOA-L
Explain the variants in Caspi’s study in 2002
those with the MAOA-L variant were more likely to grow up showing anti-social behaviour but ONLY is they had been maltreated as a child
Children with the MAOA-H variant who were maltreated and those who were MAOA-L variant who were not maltreated did not display anti-social behaviour
Explain the warrior gene with a study as well
MAOA-L is more frequent in populations with history of warfare with 2/3 having MAOA-L gene
McDermott 2009 found (L) displayed higher levels of aggression when provoked than did (H) subjects
What are the problems of sampling of genetic research
these studies have focused on individuals convicted of violent crime however they represent a minority of those regularly involving with violent crimes as some are not convicted
secondly violent based on court convictions however someone may be classed as violent but only committed one crime and had a lifetime free of crime, this may explain why studies have found little evidence of heritability
Explain difficulties determining the role of genetic factors
it is hard to establish genetic contributions to aggressive behaviour because: more than one gene contributed to a behaviour
environmental influences on aggressive behaviour
Genetic factors may affect which environmental factors have an influence and vice versa
What are the problems of assessing aggression
studies such as Miles and Carey used self-report and found genetic factors explained a large proportion of the variance in aggressive behaviour however studies using observation showed less genetic contribution and greater environmental influences
this makes it hard to assess the relative contributions of genetic and environmental factors in aggression
What is the evidence for the influence of the MAOA gene
Tihnonen 2015
What did Tihnonen 2015 do and find
studied Finnish prisoners revealing that the MAOA low-activity genotype in combination with another gene was associated with extremely violent behaviour no evidence for either of these genes among non-violent people indicating that this combination of genes was specific for violent offending only
What do critics say about Tihnonen 2015 findings
although these genes ay make it harder for some people to control urges they do not predetermine violent behaviour
How may the MAOA gene explain gender differences in aggressive behaviour
Niehoff 2014 shows that the uneven rates of violence between male and female may be a consequence of the differential genetic vunerablitlity that makes males and female have to the MAOA gene
Explain Niehoff 2014 further
MAOA is linked to X chromosome which women have two and men one. When men inherit a X-linked gene from mum they are more likely to be affected as women have a 2nd X with a normal gene for MAOA that prevents expression of abnormal version of MAOA gene this could explain why males typically show more aggressive behaviour than females
