Genetic factors Flashcards
what are dizygotic twins?
non-identical twins
what so researchers compare in twin studies?
researchers compare the degree of similarity for a particular trait (aggression) between MZ and DZ twins
what are monozygotic twins?
identical twins
what did a few studies find about aggressive behaviour in adult twin pairs?
that nearly 50% of the variance in direct aggressive behaviour could be attributed to genetic factors
how can adoption studies untangle the relative contributions of environment and heredity in aggression?
if a positive correlation is found between aggressive behaviour in adopted children and aggressive behaviour in their biological parents, a genetic effect is implied
what did the study of over 14,000 adoptions in denmark find?
that a significant number of adopted boys with criminal convictions had biological parents with criminal convictions providing evidence for a genetic effect
what is MAOA?
MAOA regulates the metabolism of serotonin in the brain and low levels of serotonin are associated with impulsive and aggressive behaviour
how does the dutch family support MAOA?
a study of a dutch family found that many of its male members behaved in a particularly violent and aggressive manner had low levels of MAOA
what study shows a gene-environment interaction?
a study was conducted involving 500 male children. researchers found that children who had low levels of MAOA and were maltreated as children were likely to exhibit aggressive behaviour as adults however children who had low levels of MAOA but werent maltreated as children did not display antisocoal behaviour
what is claimed about inherited temperamental or personality characteristics?
it places some individuals more at risk of committing violent crime
what have adoption studies shown?
the highest rates of criminal violence in adopted children occur when both biological and adoptive parents have a history of violent crime
what does low levels of MAOA lead to?
antisocial behaviour
why is it difficult to determine the role of genetic factors?
there is more than one gene that usually contributes to a given behaviour
genetic influences and environmental influences may interact with eachother
what did miles and carey meta-analysis find?
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 made use of observational ratings showed significantly less genetic contribution and a greater influence of environmental factors
what are the methodological limitations?
studies investigating role of genetic factors often fail to dinstiguish between violent and non-violent crime, making it more difficult to untangle the role of genetic factors in specifically aggressive behaviour
