Do childhood trauma and a chaotic family environment cause adult borderline personality disorder (BPD)? Common clinical wisdom says yes, but new results are leading some researchers to insist that it’s more complicated than that.
Investigators from the Minnesota Twin Family Study, first begun in 1983, collected data about childhood abuse and adult personality from 1,382 pairs of same-sex twins, followed over time from ages 11 to 24. By examining differences in abuse exposure and genetic overlap (whether the twins were identical and thus had the same DNA, or fraternal, and thus had only about 50 percent genetic overlap), the authors, led by Marina Bornovalova of the University of South Florida, concluded that childhood abuse in itself isn’t a direct cause of adult BPD traits. But since childhood abuse is seen so frequently in individuals with BPD (some studies suggest in as much as 90 percent of cases) why the overlap? According to the study, common genetic factors contribute to both childhood abuse and BPD.
The researchers suggest two possible genetically influenced reasons for the connection between childhood abuse and adult BPD. In the first model, called “passive genetic mediation,” children not only inherit genes from their parents, but are raised in an environment that’s an expression of the parents’ own genetic influences. In this model, children inherit genetic tendencies toward aggression, impulsivity, and emotional dysregulation from their parents and are raised by parents who are themselves aggressive, impulsive, and dysregulated. Abuse and BPD are thus different manifestations of the same emotionally dysregulating factors.
In a second, more controversial scenario, known as “evocative genetic mediation,” children who inherit difficult genetic temperaments from their parents tend to behave as moody or impulsive children. Emotionally intense and difficult to raise, these children strain their parents’ own genetically limited coping resources, contributing to parenting failures characterized by childhood abuse and neglect.
If the second scenario sounds like blaming the victim, the authors are quick to point out that their results “don’t support the idea that [childhood abuse] is inevitable, justified, or without harm.” However, their work raises possibly provocative questions about the causes and effects of childhood abuse and adult borderline personality disorder, once again putting science at odds with facile, politically correct perspectives on complex psychological phenomena.
What Causes Borderline Personality Disorder? Journal of Abnormal Psychology, doi: 10.1037/a0028328.