The Honest Answer
If you have wondered, Why me? Why my sister? What did we do wrong? — please hear this gently: science does not point to a single cause of BPD. It points to a mix of factors that, when they come together, can shape how a person's emotional system develops.
This is called a biopsychosocial model — meaning biology, psychology, and social environment all play a part. Let us walk through each one.
1. Biological Vulnerability
Research has shown that some people are born with a temperament that includes higher emotional sensitivity and reactivity. This is not a flaw. It is simply a way the nervous system is wired.
- Genetic studies suggest BPD has a heritability of roughly 40–60% — meaning some of the vulnerability runs in families.
- Brain imaging studies show structural and functional differences in regions like the amygdala, prefrontal cortex, and hippocampus — areas involved in emotion regulation and impulse control.
- Hormonal and biochemical factors (the HPA axis, which manages stress response; certain neurotransmitter systems) have been shown to function differently in BPD.
Important: having a biological vulnerability does not guarantee that someone will develop BPD. Many people with these traits never do. Vulnerability needs a trigger.
2. Childhood and Life Experiences
This is one of the most consistently studied risk factors. A 2021 review in Frontiers in Psychiatry analysed twenty years of research and concluded that childhood adverse experiences play a significant role in the development of BPD. These can include:
- Emotional, physical, or sexual abuse
- Emotional neglect (feelings being ignored, dismissed, or punished)
- Repeated invalidation (being told you are "too sensitive," "too dramatic," or that your feelings do not match reality)
- Unstable or chaotic home environments
- Loss of a parent or caregiver
- Bullying or sustained peer rejection
A key concept in BPD research is the "invalidating environment" — a setting where a child's emotional reality is repeatedly dismissed. Dr Marsha Linehan, who developed DBT, proposed that BPD often emerges when an emotionally sensitive child grows up in an environment that cannot meet that sensitivity with understanding. The mismatch shapes how the child learns to handle feelings.
Important again: not everyone with BPD experienced childhood trauma, and not everyone who experienced trauma develops BPD. The risk is real, but it is not a guarantee, and it is not anyone's fault.
3. Stress, Loss, and Adult Experiences
Even for someone with vulnerability and a difficult childhood, BPD often emerges or worsens during major life stressors in adolescence or early adulthood — moving away from home, the end of a first significant relationship, the birth of a child, the loss of a parent, or a betrayal.
4. Other Contributing Factors
- Physical health: Hormonal changes, chronic sleep deprivation, poor nutrition, and certain medical conditions can intensify emotional dysregulation.
- Cultural and social factors: Communities where emotional pain is stigmatised, or where women are expected to suppress their feelings, can make BPD harder to recognise and treat.
What This Means for You
If you live with BPD, or love someone who does: none of this is anyone's "fault." Not the person with BPD. Not necessarily her parents either — many families do their best with what they had. Even where harm was done, healing today does not require placing blame; it requires understanding what happened and what now needs care.
Knowing the contributing factors helps us know what to bring into the healing journey: a trauma-informed therapist if there is unresolved trauma, family work if relationships are still painful, gentle care for the body (sleep, nutrition, hormones), and the patience to remember that something this layered did not form overnight and will not heal overnight.
A Closing Reflection
For our sisters in faith: when we ask "why", remember the words of Allah in the Quran — "Allah does not burden a soul beyond what it can bear." This does not mean the burden is small. It means He sees, He knows, and He has not given you this without also giving you the capacity, with His help, to walk through it.
Whatever brought you here — biology, life, both — you are not alone in carrying it. With understanding, with the right support, and with mercy from the One who created you, healing is possible, bidhnillah.
Sources & Further Reading
- Bozzatello P, et al. "The role of trauma in early onset borderline personality disorder: a biopsychosocial perspective." Frontiers in Psychiatry, 2021.
- Leichsenring F, et al. "Borderline personality disorder: a comprehensive review of diagnosis and clinical presentation, etiology, treatment, and current controversies." World Psychiatry, 2024.
- Torgersen S, et al. "A twin study of personality disorders." Comprehensive Psychiatry, 41(6):416–425, 2000.
- Zanarini MC, et al. "Reported pathological childhood experiences associated with the development of borderline personality disorder." American Journal of Psychiatry, 154(8):1101–1106, 1997.
- Linehan MM. Cognitive-Behavioral Treatment of Borderline Personality Disorder. Guilford Press, 1993.
- Paris J. "Childhood trauma as an etiological factor in the personality disorders." Journal of Personality Disorders, 11(1):34–49, 1997.
- Bozzatello P, et al. "Gender differences in borderline personality disorder: a narrative review." Frontiers in Psychiatry, 2024.
- National Institute of Mental Health (NIMH). Borderline Personality Disorder.