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Genetic Factors On Aggression

A2 psychology presentation

George Filsell

on 23 April 2010

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Transcript of Genetic Factors On Aggression

Aggression Genetic Factors What is Aggression? Aggression can be defined as any act that intends to cause physical, emotional or psychological harm. So this can range from hitting someone. To name calling Or even just spreading rumours... Twin Studies Monozygotic, or identical, sharing 100% of genes Dizygotic, only sharing 50%of the genetic material Presuming that the environment in which twins grow up is relativly identical, one could assume that, if a set of monozygotic twins show more similarities in their aggresive behaviour than their dizygotic counterparts, genetic factors have a direct influence on levels of aggression... Coccaro et al. ,1997 Found that, 50% of the variance in direct aggressive behaviour of adult twins....Could be attributed to genetic factors Adoption Studies Adoption studies help to make a clear distinction between environmental factors and genetic factors when looking at aggression So, if a child is adopted, but regardless of the influence of their adoptive parents, turns out aggressive, matching the aggressive bahaviour of his biological father (whom he has never met) one could assume a biological, genetic link to aggression. Adversly, if an adoptive child takes on the aggressive behaviour of it's adopted parents, regardless of how the biological parent may have been, then an environmental or behavioural effect is implied. Hutchings and Mednick 1975 In a study in Denmark, of over 14,000 adoptions, it was found that of all the adopted children that turned out to have criminal convictions, the majority also had parents ( mainly fathers ) with criminal records. Providing significant support for a genetic effect Although no specific gene for controlling aggression has been found, a gene for producing the protein known as MAOA has been discovered MAOA is a protein that regulates serotonin levels in the brain Low serotonin levels are linked with impulsive and violent behaviour. Have a look at Jerry for an example... Brunner et al., 1993 Brunner studied a Dutch family, who's male members were unusually aggressive, with a large proportion being involved in violent crimes, such as rape and arson. These men were found to have extremely low levels of MAOA in their bodies and a defect in the gene which controls MAOA was later identified. Providing further support for genetic effects Difficulties In Determining The Role Of Genetic Factors Scientists havn't yet discovered a single gene that controls aggression levels, so we can't be sure on what is actually causing people's individual differences As well as there being genetic factors making it difficult to determine how aggressive behaviour manifests, there are also environmental factors that have an affect upon aggression.. These factors may well influence eachother, with genetics having an effect on how much your environment influences aggression and your environment effecting how your genetic material might manifest itself This means that stating only genetics have an affect on aggression is reductionist Violence Is Subjective What the experimenter feels qualifies as violence may not match what the pps. feels is violent and some studies into violent offenders also forget to take into account the circumstance of the crimes and the degrees of violence, not distinguishing between first time offenders and habitual criminals... Walters (1992) Walters completed a meta analysis on criminal violence and found a low to moderate correlation between heredity and crime.
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