Biological Explanations of Aggression

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Biological Explanations of Aggression
Genetic factors

One biological explanation of aggression includes genetic factors.  Studies into aggression often find aggressive children have aggressive parents.  One explanation of this is that aggression is inherited genetically.  Miles and Carey carried out a meta-analysis of 24 twin and adoption studies and found that genes could account for 50% of the variance in aggression.  This suggests aggression can be passed on genetically.  Other research has focused on indentifying important characteristics of genes that may cause aggressive tendencies, particularly focusing on chromosomes.  Sandberg indentified the ‘47XYY karyotype’.  While a normal individual has 46 chromosomes (23 from each parent) it is possible that males have an extra Y chromosome.  As males are generally thought of as more aggressive it was thought having an extra Y chromosome (male chromosome) would increase their aggression.  Court-Brown even suggested XYY males would be ‘best hospitalised due to an increased likelihood of aggressive behaviour’.

A weakness into the theory that genes influence aggression is that it ignores the behavioural approach.  This means that by focusing solely on biology (genetics), the theory ignores the role learning may play in aggression.  For example, Bandura demonstrated children learned through Social Learning Theory to be aggressive towards a Bobo Doll after observing an adult being aggressive.  This is a problem because it suggests that learning also plays a role in aggression, so a purely biological approach may be too narrow.

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Another weakness of the theory is that it is deterministic.  This means that it assumes that every XYY male will be aggressive.  For example, since this time, it has been shown that males with this gene aren’t aggressive if they choose not to be (it should also be noted recent research shows that the gene isn’t strongly linked to aggression).  This is a problem because it ignores the human characteristic of free will.

Evidence to support the role of genes in aggressive behaviour comes from Lagerspetz.  He bred 25 generations of mice, choosing the most aggressive to breed together and ...

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