Mental health has a great impact on an individual’s life. It affects their ability to cope with daily events and activities and their ability to relate to others. Research from the National Institute of Mental Health (NIMH, 2024) shows that mental health conditions likely result from a combination of life experiences, the environment, and genetic variation. In addition, a growing body of research shows that specific gene variations are associated with mental health conditions. As such, genetics plays a notable role in mental health.
Mental Health Conditions That Run in Families
Scientists and researchers have long recognized that most psychiatric conditions tend to run in families, which points to possible genetic roots (Stoewen, 2022). These conditions include attention deficit hyperactivity disorder (ADHD), autism, bipolar disorder, schizophrenia, and major depression (Sullivan et al., 2012). Their symptoms tend to overlap, making it hard to distinguish between the five syndromes. Just as they share symptoms, they probably also share similarities at the biological level. Recent studies show limited evidence of common genetic risk factors between bipolar disorder and schizophrenia, schizophrenia and autism, and bipolar disorder and depression. Therefore, research indicates a probable relationship between family roots and mental health conditions.
Heritability estimate of each disorder, %
- Schizophrenia: 81 %.
- Autism spectrum disorder: 80 %.
- ADHD: 75 %.
- Bipolar disorder: 75 %.
- Major depressive disorder: 37 %.
None of the five reaches 100%, which is the post’s point that no mental disorder is entirely genetic. Major depression, the most common of the five, is also the least heritable, so environment and life events carry more of its risk.
Chart by Writers Per Hour. Figures: Sullivan, P. F., Daly, M. J., & O’Donovan, M. (2012), Genetic architectures of psychiatric disorders, Nature Reviews Genetics, 13(8), 537–551, Table 1.
Show the figures as a table
| Disorder | Heritability (%) |
|---|---|
| Schizophrenia | 81 |
| Autism spectrum disorder | 80 |
| ADHD | 75 |
| Bipolar disorder | 75 |
| Major depressive disorder | 37 |
Family History as a Risk Indicator
An individual’s family history is among the best ways of determining the risk of a mental disorder. Various conditions run in families, and having a close relative with such an illness could mean that a person is at a higher risk of developing it. However, this does not mean that if one family member has a condition, all their relatives will develop it. Family history shows a likelihood, not a certainty. Doctors recommend knowing the family’s mental health history because it helps to identify the risk of mental health challenges. It also helps individuals identify actions that will reduce the risk and recognize early warning signs. Consequently, family history shows the likelihood of developing a mental health disorder.
Genetic Testing and Bipolar Disorder
Genetic tests are another way to study the risk of mental health conditions, but they are not yet a clinical tool for it. NIMH (2024) states that genetic tests cannot accurately predict a person’s risk of developing a mental disorder and that it is still too early to use them to diagnose or treat these conditions. Research on bipolar disorder shows why. It is among the most heritable mental conditions: it affects about 0.7% of people during their lifetime, and around 75% of the variation in risk is attributed to genetic factors (Sullivan et al., 2012). Large genome-wide studies have linked the disorder to common variants in or near genes such as ODZ4, CACNA1C, NCAN, and ANK3, yet each of these variants raises the odds of the disorder by only about 10% to 20% (Sullivan et al., 2012). Because the risk is spread across many small effects, no single test result can show who will develop the condition. Therefore, genetics is clearly related to mental health, even though a test cannot yet measure that relationship for one person.
Why No Mental Disorder Is Entirely Genetic
Despite the relationship between genetics and mental health, no mental disorder is 100% heritable. Even schizophrenia, the most heritable of the five conditions above, has a heritability estimate of about 81% (Sullivan et al., 2012). Various factors create the likelihood of developing a specific disorder, whether genetic risk factors are present or absent. Most disorders have multifactorial origins, and researchers now study genes and the environment as interacting causes rather than independent ones (Navarro-Mateu et al., 2013). Therefore, mental illnesses are caused by various factors, and none of them has purely genetic roots.
Conclusion
In summary, genetics plays a notable role in mental health. Scientists and researchers have long recognized a probable relationship between family roots and mental health conditions. Family history is among the best ways of determining the risk of mental disorders, while many common gene variants each add a small part of that risk. However, genetic tests cannot yet predict who will develop a disorder, and no mental disorder is 100% heritable or has a purely genetic basis.
