While movies and visual media often sensationalize people with BPD by portraying them as violent, the majority of researchers agree that people with BPD are unlikely to physically harm others. Although people with BPD often struggle with experiences of intense anger, a defining characteristic of BPD is that they direct it inward toward themselves. One of the key differences between BPD and antisocial personality disorder (ASPD) is that people with BPD tend to internalize anger by hurting themselves, while people with ASPD tend to externalize it by hurting others.One 2020 study found that BPD is individually associated with psychological, physical and sexual forms of intimate partner violence (IPV), especially amongst men. In terms of the AMPD trait facets, hostility (negative affectivity), suspiciousness (negative affectivity) and risk taking (disinhibition) were most strongly associated with IPV perpetration for the total sample.In addition, adults with BPD have often experienced abuse in childhood, so many people with BPD adopt a "no-tolerance" policy toward expressions of anger of any kind. Their extreme aversion to violence can cause many people with BPD to overcompensate and experience difficulties being assertive and expressing their needs. This is one way in which people with BPD choose to harm themselves over potentially causing harm to others. Another way in which people with BPD avoid expressing their anger through violence is by causing physical damage to themselves, such as engaging in non-suicidal self-injury.
An unstable family environment predicts the development of the disorder, while a stable family environment predicts a lower risk. One possible explanation is that a stable environment buffers against its development. Self-complexity
Self-complexity, or considering ones self to have many different characteristics, may lessen the apparent discrepancy between an actual self and a desired self-image. Higher self-complexity may lead a person to desire more characteristics instead of better characteristics; if there is any belief that characteristics should have been acquired, these may be more likely to have been experienced as examples rather than considered as abstract qualities. The concept of a norm does not necessarily involve the description of the attributes that represent the norm: cognition of the norm may only involve the understanding of "being like", a concrete relation and not an attribute. Thought suppression
A 2005 study found that thought suppression, or conscious attempts to avoid thinking certain thoughts, mediates the relationship between emotional vulnerability and BPD symptoms. A later study found that the relationship between emotional vulnerability and BPD symptoms is not necessarily mediated by thought suppression. However, this study did find that thought suppression mediates the relationship between an invalidating environment and BPD symptoms. Developmental theories
Marsha Linehans biosocial developmental theory of borderline personality disorder suggests that BPD emerges from the combination of an emotionally vulnerable child, and an invalidating environment. Emotional vulnerability may consist of biological, inherited factors that affect a childs temperament.