What Causes Borderline Personality Disorder?

If you live with Borderline Personality Disorder (BPD), you may have spent a lot of time wondering, Why do I react this way? Why do my emotions feel so intense? Why do relationships sometimes feel wonderful one moment and unbearable the next?

You may even have wondered whether something happened to you that caused it, or whether there is simply something fundamentally wrong with you.

The truth is much more complicated, and much more hopeful.

There is no single cause of Borderline Personality Disorder. Research suggests that BPD develops through an interaction between biological vulnerability, temperament, emotional processes, relationships, and life experiences. Understanding these different influences can help make sense of BPD without placing blame on you, your family, or your past.

It Is Not Just One Thing

BPD does not develop because of one particular childhood experience, one difficult relationship, or one genetic factor.

Instead, think of it as several pieces coming together over time.

Some people may be born with a nervous system that is especially sensitive to emotional experiences. They may feel things intensely, react quickly to changes around them, or have more difficulty returning to a calm emotional state after becoming upset.

For someone with this kind of sensitivity, experiences that might be manageable for another person can feel much more powerful. A disagreement with someone you love may feel deeply threatening. Rejection may feel devastating. Uncertainty in a relationship may be difficult to tolerate.

This does not mean that the person is choosing to be overly emotional. Their emotional system may simply be responding with greater intensity.

What Does Childhood Have to Do With BPD?

When researchers study BPD, they often find associations with difficult childhood experiences, including neglect, abuse, inconsistent caregiving, and environments in which a child's emotional experiences were frequently dismissed or invalidated (Porter et al., 2020).

These experiences can affect how a person learns to understand emotions, relationships, trust, and their own sense of worth.

Imagine growing up feeling that your emotions were too much, wrong, unpredictable, or unwelcome. You may not have had many opportunities to learn that strong emotions can be experienced without acting on them, or that conflict within a relationship does not necessarily mean the relationship is ending.

Over time, these experiences can influence the ways you respond to closeness, rejection, conflict, and emotional distress.

But there is an important distinction here: childhood adversity is a risk factor, not a cause that applies to everyone with BPD.

Many people experience childhood trauma and never develop BPD. And not everyone with BPD has experienced significant childhood trauma. Researchers therefore view BPD as the result of multiple interacting factors rather than a simple response to something that happened during childhood (Porter et al., 2020).

Your Brain and Nervous System Matter Too

Our emotional responses are influenced by the brain and nervous system, and research suggests that people with BPD may differ in the way they process and regulate emotional information.

This may contribute to heightened emotional reactivity, difficulties calming down after becoming distressed, and impulsive responses during periods of intense emotion.

Importantly, this does not mean that the brain is permanently damaged or that BPD is something a person simply has to live with forever.

The brain is capable of learning and adapting. Repeated experiences, relationships, and therapeutic skills can influence how we respond to emotions over time.

This is one reason treatment can be so valuable. Therapy is not simply about talking about your childhood. It can help you develop new ways of responding to emotions, relationships, and stressful situations in the present.

Why Can Relationships Feel So Intense?

Relationships can become especially important when someone is living with BPD.

A person may deeply want closeness and connection while simultaneously feeling terrified of losing it. A small change in someone's behaviour can sometimes trigger powerful fears of rejection or abandonment.

A delayed text might feel like a sign that someone is pulling away. A disagreement might feel like the relationship is ending. A moment of distance might create an urgent need for reassurance.

These reactions can sometimes lead to behaviours that unintentionally make relationships more difficult. Someone might repeatedly seek reassurance, become angry, withdraw, test the relationship, or end things before they can be rejected.

From the outside, these reactions can be difficult to understand. From inside the experience, they may feel like desperate attempts to make an uncertain relationship feel safe again.

Understanding this pattern does not mean that every behaviour is healthy or that other people should accept harmful behaviour. It means that there is often an emotional story underneath the behaviour, and that story can be explored and changed.

So, Is BPD Genetic?

There appears to be a heritable component to BPD, meaning that genetic factors may contribute to a person's vulnerability. But genes do not determine whether someone will develop BPD.

This is an important distinction.

Having a biological or genetic vulnerability does not mean that BPD is inevitable. Environmental experiences, relationships, coping strategies, and other factors interact with biological predispositions throughout development.

In other words, there is no single “BPD gene.” The condition is better understood as emerging from a complex combination of influences rather than one predetermined pathway.

Understanding the Past Without Getting Stuck There

Learning about the possible causes of BPD can be helpful, particularly if you have spent years blaming yourself for your emotional reactions.

It can be relieving to understand that intense emotional responses are not simply a character flaw.

At the same time, understanding why something developed is only part of the process. The more important question may eventually become:

What can I do differently now?

That is where therapy can make a meaningful difference.

BPD Is Treatable

One of the most important things to know about Borderline Personality Disorder is that it is treatable. Several forms of psychotherapy have demonstrated benefits for people with BPD, including Dialectical Behaviour Therapy, Mentalization-Based Treatment, Schema Therapy, and other structured approaches (Rameckers et al., 2021; Setkowski et al., 2023; Stoffers-Winterling et al., 2022).

Therapy can help you recognize emotional triggers before they become overwhelming, develop skills for managing distress, communicate more effectively, understand relationship patterns, and build a stronger sense of who you are.

It can also help you develop something that may have felt out of reach for a long time: the ability to experience a powerful emotion without immediately having to act on it.

That space between feeling and responding can become incredibly important.

You Are More Than Your Diagnosis

A diagnosis of BPD can sometimes become an explanation for everything a person does. It can also carry a great deal of stigma.

But BPD is not a description of your character.

It does not mean that you are manipulative, incapable of having healthy relationships, or destined to struggle forever. It means that you are experiencing a particular pattern of emotional and interpersonal difficulties that can be understood and treated.

The reasons BPD develops are different for every person. Your history matters, your biology matters, and your relationships matter. But none of these things has to determine the rest of your life.

If you recognize yourself in the experiences described here, therapy can be an opportunity to understand your patterns with compassion rather than judgement and begin developing new ways of responding.

At Authentic Living London, Sandra Graham offers therapy for people experiencing the emotional and relationship difficulties associated with Borderline Personality Disorder. The goal is not to erase your emotions or change your personality. It is to help you understand yourself more deeply, develop greater emotional stability, strengthen your relationships, and build a life that feels more manageable and fulfilling.

If you are looking for therapy for Borderline Personality Disorder in London, Ontario, we invite you to reach out for a free 15-minute phone or video consultation.

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Sandra Graham BSc, MACP, is a psychotherapist at Authentic Living London with a specialized focus on personality disorders. She works with individuals navigating the challenges of Borderline Personality Disorder, Narcissistic Personality Disorder, and other personality-related difficulties. Sandra’s approach is grounded in empathy, understanding, and evidence-based methods, providing clients with a safe space to explore patterns, develop coping strategies, and gain insight into themselves and their relationships.

References

Porter, C., Palmier-Claus, J., Branitsky, A., Mansell, W., Warwick, H., & Varese, F. (2020). Childhood adversity and borderline personality disorder: A meta-analysis. Acta Psychiatrica Scandinavica, 141(1), 6–20. https://doi.org/10.1111/acps.13118

Rameckers, S. A., Verhoef, R. E. J., Grasman, R. P. P., Cox, W. R., van Emmerik, A. A. P., Engelmoer, I. M., & Arntz, A. (2021). Effectiveness of psychological treatments for borderline personality disorder and predictors of treatment outcomes: A multivariate multilevel meta-analysis of data from all design types. Journal of Clinical Medicine, 10(23), 5622. https://doi.org/10.3390/jcm10235622

Setkowski, K., Palantza, C., van Ballegooijen, W., Gilissen, R., Oud, M., Cristea, I. A., Noma, H., Furukawa, T. A., Arntz, A., van Balkom, A. J. L. M., & Cuijpers, P. (2023). Which psychotherapy is most effective and acceptable in the treatment of adults with a (sub)clinical borderline personality disorder? A systematic review and network meta-analysis. Psychological Medicine, 53(8), 3261–3280. https://doi.org/10.1017/S0033291723000685

Stoffers-Winterling, J., Storebø, O. J., Kongerslev, M. T., Faltinsen, E., Todorovac, A., Jørgensen, M. S., Sales, C. P., Callesen, H. E., Ribeiro, J. P., Völlm, B. A., Lieb, K., & Simonsen, E. (2022). Psychotherapies for borderline personality disorder: A focused systematic review and meta-analysis. The British Journal of Psychiatry, 221(3), 538–552. https://doi.org/10.1192/bjp.2021.204