Certain studies have suggested that borderline personality disorder (BPD) is up to 67 per cent heritable (e.g. Torgenson et al. 2000 and 2012). In other words, these studies suggest there is a large genetic component that contributes to an individual’s chances of developing BPD during adulthood. This, in turn, suggests (but does not prove) that certain behavioural aspects/traits of BPD may well have been adaptive for our ancestors (i.e. helped them to cope with their environment, to survive and, ultimately, therefore, to reproduce in certain situations). Let’s look at examples of why this may have been the case.
EXAMPLE 1: SOCIAL AVOIDANCE
One aspect of personality pathology can be social avoidance (e.g socially avoidant personality disorder and the BPD during phases of withdrawal) This trait could have helped our ancestors survive if they lived in an environment in which there existed many dangerous strangers.
EXAMPLE 2: IMPULSIVE BEHAVIOUR
Many individuals suffering from BPD are highly impulsive. If a person is impulsive, it means s/he tends to react very quickly to an array of stimuli. Thus, in environments in which danger could suddenly come out of nowhere (like being unexpectedly attacked by a predator), lighting fast reactions would help to increase the individual’s chances of survival.
EXAMPLE 3: AGGRESSION
One main symptom of BPD is a propensity to fly into intense rages and become (usually verbally) aggressive. Again, for our ancestors, aggression helped them to survive and reproduce. Indeed, violence was necessary as there was no police force to protect people and food and resources could sometimes only be gained by the means of fighting. Even during the last century, anthropologists studied a tribe of very violent hunter-gatherers and found that those who had committed homicide lived longer and reproduced more than less violent members of the tribe.
DOUBLE-WHAMMY: THE EFFECT OF A COMBINATION OF GENETIC RISK FACTORS AND CHILDHOOD ENVIRONMENTAL FACTORS ON RISK OF DEVELOPING PERSONALITY PATHOLOGY IN ADULT LIFE:
It stands to reason that individuals who both inherit traits relevant to BPD and grow up in a dysfunctional environment (constituting a ”double-whammy) are at especially increased risk of developing BPD compared to both those who inherit similar traits but experience a stable and loving childhood and those who do not inherit BPD-related traits but experience a traumatic and stressful childhood. It follows, of course, that if a parent has BPD the child is at significantly increased risk of developing BPD him/herself as s/he may both inherit predisposing personality traits and grow up in a harmful environment.
David Hosier BSc Hons; MSc; PGDE(FAHE).