Researchers do know from twin studies that genetics plays a role in personality disorders. Environmental factors, such as childhood abuse, neglect and separation from caregivers, as well as brain abnormalities, emotion regulation, impulsivity, aggression and serotonin levels all play a role.ecause many personality domains are heritable, borderline personality disorder may be a result of a genotype interacting with adverse environmental factors. This would in turn lead to the expression of borderline symptoms or other dysfunctional personality traits.