Is Borderline Personality Disorder Genetic?

Borderline personality disorder (BPD) can be genetic, but the risk of developing BPD is also influenced by unique environmental factors. BPD is a mental health condition characterized by instability in moods, self-image, and behavior.

The symptoms of borderline personality disorder typically begin in the adolescent years, and the condition is more common in females.

This article discusses the causes and risk factors for BPD, as well as symptoms associated with BPD and how it is treated.

What Is Borderline Personality Disorder?

BPD is a mental health condition characterized by instability in moods, self-image, and behavior. People with BPD may have unstable relationships; intense episodes of anger, anxiety, or depression; and impulsive, even self-harming, actions.

BPD affects 1.4% of the U.S. population. You are more likely to develop BPD if a member of your family has the condition, and your risk increases depending on how closely related you are to the person with BPD. The heritability of BPD (the chance that you will inherit the trait) is estimated to be 46%.

Borderline Personality Disorder and Genetics

Current research supports the theory that there is a large genetic component to whether a person develops BPD. Two genes—DPYD and PKP4—have been identified as increasing a person's risk of developing BPD. However, these genes are linked to schizophrenia and bipolar disorder risk, too.

Researchers use "hazard ratios" to describe this risk, which essentially indicate the increased likelihood for you to develop BPD versus someone in the general population who has no genetic relation to someone with BPD.

The hazard ratios for BPD are as follows:

• Identical (monozygotic) twins: 11.5
• Fraternal (dizygotic) twins: 7.4
• Full siblings: 4.7
• Maternal half-siblings: 2.1
• Paternal half-siblings: 1.3
• Cousins whose parents were full siblings: 1.7
• Cousins whose parents were maternal half-siblings: 1.9

For example, if your full sibling has BPD, you are 4.7 times more likely to develop it than someone who is unrelated to anyone with BPD. That said, the prevalence of BPD across populations is 1.4%—meaning that you are still more likely to not develop BPD, even though you are at greater risk.

However, first-degree relatives also share environments, which means that these findings do not point solely to genetics. Environmental causes, particularly childhood trauma, abuse, and neglect, also contribute to the development of BPD. That's why looking at twin studies is helpful in understanding the true genetic contribution to BPD.

Twin Studies

Twin studies use identical twins (who share 100% of their DNA) and fraternal twins (who share 50% of their DNA) as participants. These types of studies are essential to understanding genetics because they help researchers disentangle genetic causes from environmental causes in order to make more accurate conclusions about heritability.

For example, if identical twins raised in different environments have similar hazard ratios for developing BPD, it suggests that genetics has a stronger role than environment in the development of the disease.

In 2019, a large-scale Swedish twin study (and the highest-quality twin study on BPD performed to date) found that identical twins were significantly more likely to develop BPD than fraternal twins (hazard ratios of 11.5 to 7.4, respectively).

The study concluded that clusters of BPD in families have genetic causes and are not caused by shared environmental factors (such as socioeconomic status). That means that if those identical twins had been separated and grew up in different environments, their likelihood of developing BPD would remain the same based on their genes.

However, the researchers did conclude that there is a 54% contribution of unique, non-shared environmental factors—such as trauma or abuse—which could explain variance. In other words, genetics plays a large role in whether you may develop BPD, but it is not the only factor.

Other Risk Factors for BPD

Studies have also found an association between environmental factors and BPD. However, the research is largely associative, making it difficult to conclude the cause-and-effect relationship between these factors and BPD.

Some evidence supports a link between distressing childhood experiences (particularly involving caregivers) and the development of BPD. Childhood experiences that may be associated with BPD include:

• Early separation from caregivers
• Emotional or physical neglect
• Parental insensitivity
• Physical and sexual abuse

Signs and Symptoms of BPD

A person with untreated or poorly treated BPD may feel overly emotional, with frequent outbursts of anger, self-hate, or self-harm.

They often have unstable relationships, pushing away their loved ones while simultaneously experiencing a deep fear of abandonment. They may also make impulsive and dangerous decisions, increasing their likelihood of substance use.

The signs and symptoms of BPD are set out by the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition" (DSM-5)—the handbook used to diagnose mental health conditions.

A person must have five or more of the following symptoms to be diagnosed with BPD:

• Efforts to avoid abandonment
• Impulsive behaviors
• Intense episodes of anger
• Emotional instability
• Feelings of emptiness
• Identity and self-image disturbances
• Unstable relationships
• Self-harming behaviors, including suicidal behaviors
• Paranoid or dissociative symptoms that pass quickly
  

Why Treatment Matters

Early intervention for BPD, as well as any co-occurring conditions, is very important. It used to be believed that BPD was untreatable. However, a variety of new models of psychotherapy have been developed over the past several decades to help people with BPD.

BPD should only be delivered by a specially trained provider. Research has found that BPD responds very well to treatment using the following psychotherapies:

• Dialectical behavior therapy (DBT): a type of talk therapy cognitive behavioral therapy (CBT) that is adapted for people who feel emotions very intensely
• Mentalization-based therapy (MBT): a therapy that encourages an individual to focus on how their thoughts and feelings affect their behavior, as well as the effects on the thoughts, feelings, and behavior of others
• Transference-focused therapy (TFB): a type of psychotherapy that uses the person's relationship with their therapist to change how they relate to other people. This may help to identify problematic thoughts, develop healthier behaviors, and improve social interactions.
• Schema-focused therapy (SFT): a therapy that helps people to change their entrenched, self-defeating life patterns (schemas) using cognitive, behavioral, and emotion-focused techniques.

Medications can also be prescribed to treat comorbid conditions (conditions that occur at the same time but are usually independent of another condition), such as depression and anxiety. However, there is no medication approved by the Food and Drug Administration (FDA) to specifically treat BPD.

A person with well-treated BPD may find that many of their symptoms decrease—or at least become more easily managed—by learning how to track symptoms, avoid triggers, and seek support when needed. They will learn coping mechanisms to prevent self-harm, maintain relationships, and manage their roller coaster of emotions.

Some people even find that with continuous treatment they no longer meet the diagnostic criteria for BPD.

Having Kids When You Have BPD

If you have BPD, you may have mixed feelings about having children. If you are concerned about the possibility that your children will also have BPD, know that just because you have the condition does not mean that your children also will. However, due to genetic factors, your children will be at an increased risk of developing BPD compared to the general population.

Unique environmental factors such as abuse, trauma, and neglect are associated with BPD. You can lower the chances of your child developing BPD by doing your best to raise your child in a safe and supportive environment where they are surrounded by responsible adults and caregivers.

Seeking treatment for your own BPD will also support your child's development. Your BPD may not go away, but you can prepare yourself for the task of raising children by developing helpful coping mechanisms, undergoing psychotherapy, and taking medications as prescribed.

As a parent with BPD, you might be more likely to recognize the signs and symptoms of the condition in your child. This can be an asset, as they will likely be diagnosed sooner and get treatment quicker.

Summary

Borderline personality disorder is a complex and serious mental health condition. While it does have significant genetic factors, the risk of developing BPD is also influenced by environmental factors.

There is a lot that is still unknown about the genetics of BPD, but symptoms can include feeling overly emotional (with frequent outbursts of anger, self-hate, or self-harm) and having unstable relationships. Several therapeutic modalities are effective in treating BPD.

If you are concerned about having children if you have BPD, talking with your therapist or seeking the input of a genetic counselor can help you process your concerns and reach a decision that you feel comfortable with.