Monoamine oxidase A (MAO-A), is an enzyme that in humans is encoded by the MAO-A gene, a version of which has been popularly referred to as the Warrior Gene. Several different versions of the gene are found in different individuals, although a functional gene is present in most humans (with the exception of a few individuals with Brunner syndrome, a rare genetic disorder). MAO aids in the breakdown of neurotransmitters such as serotonin and dopamine and are, therefore, capable of influencing the feelings, moods, and behaviors of individuals.
According to this, if there was a mutation to the gene that is involved in the process of promoting or inhibiting MAO enzymes, it could affect a person’s personality and could therefore make them more prone to aggression. A deficiency in the MAO-A gene has been linked to higher levels of aggression in males. In a 2009 criminal trial in the US, an argument based on a combination of ‘warrior gene’ and history of child abuse was successfully used to avoid a conviction of first-degree murder and the death penalty; however, the convicted murderer was sentenced to 32 years in prison.
The Daily Omnivore 