Genetic Factors In Aggressive Behaviour Essay

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Register to read the introduction… If a positive correlation is found between aggressive behaviour in adopted children and aggressive behaviour in their biological parents, a genetic effect is implied. However, if a positive correlation is found between the adoptee’s aggressive behaviour and the rearing family, then an environmental effect is implied. Although, research by Hutchings and Medinick suggests that environmental factors do not play a role in aggressive behaviour, as they found when looking at 14,000 adoptions in Denmark that there was a significant number of adopted boys with criminal convictions who had biological parents with criminal convictions. This also provides evidence for a genetic effect and implies that aggressive behaviour can be passed down to individual’s offspring. Adoption studies have shown that the highest rates of criminal violence occur when both biological and adoptive parents have history of carrying out a violent crime – this is clear evidence of gene-environment …show more content…
Although there is no individual gene that has been identified in humans, a gene responsible for producing a protein called monoamine oxidase, this has been associated with aggressive behaviour. This causes serotonin levels to be low, and this leads to impulsive and aggressive behaviour. For example, in the 1980’s a Dutch family found that many of its male members behaved in a particularly violent and aggressive manner, and a large proportion had been involved in serious crimes of violence such as rape. These men were found to have abnormally low levels of MAOA in their bodies, and a defect in this gene was later identified. This research represents that hormones and the internal mechanisms of your body has a high level of impact on an individual’s anti-social behaviour for example, aggression.
Research that supports this theory of genetics heavily influencing the behaviour of violence was carried out in a meta-analysis by Miles and Carey, who reviewed 24 twin and adoption studies. Most studies had relied on paternal or participants’ self-reports of aggressive tendencies, although some involved observation of aggressive behaviour. The results showed there is a strong genetic influence that could account for as much as 50% of variances in
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Disputing research to the claim that aggression caused by genetics is a replication of Bandura et al.’s Bobo doll study. Twin pairs were encouraged to act aggressively towards the doll by being exposed to an adult model who acted aggressively towards it. Researchers found no difference in correlations between monozygotic and dizygotic twin pairs, suggesting that individual differences in aggression were more a product of environmental influences for example a family upbringing, rather than genetic

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