Cases breaks the ethical consideration of refinement. For example, the sample were genetically modified to have MAOA-L. This is an issue because this GM is irreversible and caused aggression displayed in distressing symptoms for the mice. To rectify this, Cases et al could have used a chemical to prevent the production of the enzymes without genetically modifying, and so avoiding the issues that would cause. However, the GM could be necessary as a chemical use would reduce causality of the aggression, as it is not a change from birth like GM, and so would create extraneous variables, and a likely only correlational relationship. Therefore, ethical considerations are not met, but this is necessary when examining genetics and behaviour.