Outline the role of genetic factors in aggressive behaviour. (4 marks)

Briefly outline the role of genetic factors. Make sure you don't spend too much time on this question!


One gene which has been linked to aggression is the gene coding for the production of monoamine oxidise A (MAOA). MAOA regulates the metabolism of serotonin in the brain, and low levels of serotonin are associated with aggressive behaviour. Thus, low levels of MAOA are also associated with aggression. Studies of violent criminals have found that they often have a defect in the gene that produces MAOA.

Gene variants can also affect the production of testosterone, a hormone which increases levels of aggression. Sex hormone-binding globulin (SHBG) is a glycoprotein that binds to hormones such as testosterone, but a common variant in the gene coding for the production in SHBG can result in lower levels of SHBG being produced. This means that there are higher concentrations of unbinded testosterone, causing the body produces less testosterone. Thus, inheriting these gene variants can decrease levels of aggression.

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