It is well-known that males tend to be more aggressive, boisterous and dominating than women. Women, on the other hand, tend to be more nurturing, caring, and affectionate. Studies have shown that the MAOAL-L variation is three times more common in males than it is for women. This is largely due to the fact that men have a greater chance of being heterozygous than women, and can also be homozygous. On the other hand, men are hemizygous because they only possess one X chromosome.

Notably, aggression does not necessarily occur in men only. Females with the MAOAH gene can display high levels of aggression as well as males who have the MAOAL gene. However, more activity is observed in the male area of the amygdala (Holz, et al. 2014). Also, male MAOAL-carriers and female MAOAH-carriers have been shown to experience higher hippocampal activation and greater materialisation of anger and fear. This could indicate that negative experiences can be used to stimulate aggressive behaviors (Denson-et al. (2009)). The MAOA/L genotype, which is controversial, has been shown to be associated with observable happiness among women. According to a recent study, the MAOA-L gene has been linked to happiness in women. The accuracy of this experiment is not yet known (Chen and co., 2013). However, low estrogen levels in women during menstruation can lead to emotional and psychological stress as well as violent probabilities (Staniloiu, Marksowitch (2012)). It has been shown that social aggression is linked to low testosterone and high cortisol in males. Testosterone and cortisol are both end products contrived in the hypothalamus-pituitary-adrenal axis (HPA) and this neuropathological region of the brain is devoted to motivation and reward seeking pathways. A high testosterone/low level of cortisol can lead to threatening and risky behavior (Terburg Morgan & Honk 2009. As most of the studies that have been done on the MAOA variant focussed on male aggression, it is clear that more research is needed to determine the effects of female testosterone/cortisol levels. The evidence is not sufficient to draw any conclusions.