Genetics

• The MAOA gene controls how much MAOA enzyme our body produces. MAOA enzyme is a chemical that breaks down leftover neurotransmitters in our synapse
• There is a less common version of the MAOA gene called the MAOA-L gene, nicknamed the 'warrior gene'. This version produces lower amounts of MAOA enzyme
• People with the MAOA-L gene have less MAOA enzyme to break down neurotransmitters in the brain, they have increased levels of the neurotransmitter serotonin. Having higher levels of serotonin is linked to being more aggressive
• The MAOA gene could explain why men are often describes ad more aggressive than women. The MAOA gene only appears on the X chromosome, as women have two X chromosomes, a male who inherits the MAOA-L gene is stuck with it
• There is evidence to support the fact that the MAOA gene influences aggression. A study showed mice who were bred so that they had no MAOA gene at all were found to be much more aggressive than normal mice. When given a drug that blocks serotonin receptors, the mice reverted to normal behaviour. This suggests that the effect of serotonin is influenced by the MAOA gene
• However as most experiments on the MAOA gene are conducted on animals. We cannot extrapolate results from animal studies to humans as humans have much more complex brains and social environments than animals. For instance, humans know that aggression can lead to social consequences. So even if genes do influence aggressive feelings, we should be less likely to act on them
• The genetic explanation of aggression is deterministic because saying that aggression is caused by genetic factors that are beyond our control implies that we have no free will to control our aggressive behaviour.
• It is also socially sensitive because genetic explanations imply that people are not responsible for their aggressive acts and therefore society has no right to punish aggressive crimes.