Is Bipolar Disorder Hereditary? Understanding Your Risk

Bipolar disorder is a mental health condition that causes extreme shifts in mood and activity levels. It also affects a person's energy, thoughts, behavior, and ability to function in daily life.

If you have bipolar disorder and are considering having children, one of the questions you are probably asking yourself is whether you would pass your bipolar disorder on to a child. Is bipolar disorder hereditary? What is the role of genetics in bipolar disorder?

This article discusses whether bipolar disorder is hereditary, other factors that may play a role, and whether having a family history of the condition may affect your decision to have children.

Is Bipolar Disorder Hereditary?

We have known for some time that bipolar disorder can run in families, and now, with genomic sequencing, we are learning about the possible role of genetic factors in the disorder. While the role of heredity is clear from family and twin studies, further research is needed.

Let's look at what we know about family history and bipolar disorder, and then at what genetic specialists have discovered about the role of individual genes in both bipolar disorder and other mental health disorders.

Family History of Bipolar Disorder

Bipolar disorder is overall considered to be one of the most heritable of mental health disorders based on a review of family history charts. Research indicates that:

• A child of one parent with bipolar disorder and one without has a 15% to 30% chance of having BP.
• If both parents have bipolar disorder, there's a 50% to 75% chance that a child of theirs will, too.
• If you already have one child with BP, there is a 15% to 25% chance that another of your children will also have it.
• If one identical twin has BP, there's about an 85% chance that the other one will as well. Studies indicate that the chance of an identical twin also having bipolar disorder ranges from 38% to 43% with that of dizygotic (non-identical) twins being between 4.5% and 5.6%.

Specific aspects of bipolar disorder also appear to run in families including the polarity of illness onset (mania vs depression,) frequency of episodes, the presence of psychosis, suicidality, rapid cycling, associated alcohol use disorders, panic disorder, and responsiveness (or lack thereof) to medications such as lithium and other drugs.

The age of onset of bipolar disorder is often younger for those children who have parents or grandparents with a more severe bipolar disorder.

Genetics vs. Environment

When bipolar disorder runs in families it begs the question: Is the increase in risk related to genetics (specific gene combinations) or the environment (who we are, including our early childhood experiences, how we were raised, our social relationships, and our surrounding culture).

It appears that both mechanisms are probably at play and contribute to the causation of bipolar disorder. Epigenetics, the study of whether, how, and when genes are expressed, explains that certain environmental factors determine the expression of genes or even turn certain genes on or off in the next generation. 

Other Risk Factors

Other risk factors that can play a part in the onset of bipolar disorder include:

• Traumatic or stressful events: Experiencing a very traumatic or stressful event, such as the sudden death of a loved one, can trigger bipolar episodes. Illness, divorce, and financial problems are examples of stressors that can increase the risk of experiencing bipolar mania or depression
• Substance use: Using drugs and alcohol also increases the risk of developing bipolar disorder.
• Differences in brain structure: While more research is needed, people who develop bipolar disorder may be more likely to have structural differences in the brain that play a part.

The Genetics of Bipolar Disorder

Though it runs in families, it is harder to define specific genetic risk factors. Studies looking at the genetics of bipolar disorder have failed to find a single gene that is causative (for example, as is the case with cystic fibrosis.)

Variants in genes such as ANK3, CACNA1C, NCAN, ODZ4 and are thought to increase susceptibility but explain only a very small percentage of the genetic risk. In addition, the majority of people with these "at-risk alleles" do not have bipolar disorder.

Genetics and Bipolar Medications

A separate issue that has been noted with our newer understanding of genetics is that genetics may play a role in how a person responds to medications for bipolar disorder.

For example, those with two inactive copies of the CYP206 gene may be poor metabolizers of drugs such as risperidone and aripiprazole. As noted above, how much a person responds to drugs such as lithium may run in the family.

Should You Have Children If You Have Bipolar Disorder?

Knowing that there is an increased risk of bipolar disorder in children of those with bipolar disorder, should parents with the disorder have children?

This is a question that doesn't have a right or wrong answer. There are many medical conditions that may have a hereditary aspect. In addition, there is not a single gene or gene sequence that "guarantees" a child will develop bipolar disorder.

It's important to note that nothing says that having a child who does develop a mental health disorder will not be a wonderfully fulfilling experience.

A Word From Verywell

It seems clear that there is a genetic role in the development of bipolar disorder, but this role appears to be polygenic (controlled a little bit by many different genes) and very complex. In other words, there is not a single or even several gene variations that cause bipolar disorder.

Instead, it is a diverse combination of genes that may increase a person's susceptibility to developing bipolar disorder.

A family history of the disorder is not a reason to put off becoming a parent. You may wish to learn about the red flags for bipolar disorder in children, and the different forms of the disorder.