In a landmark study challenging widespread beliefs about heredity and mental health, researchers have found that the majority of cases of serious mental illnesses such as schizophrenia, bipolar disorder, and depression arise in individuals with no close family history of these conditions. The research, covering data from over 3 million people, calls for a shift in how mental health is understood and addressed both globally and within Thailand’s evolving mental health landscape (Neuroscience News).
This breakthrough analysis, conducted at Aarhus University’s Danish Center for Register-Based Research and published in The Lancet Psychiatry, has major implications for public health policy, education, social stigma, and treatment strategies. For many Thais concerned about their own risks – or burdened by misconceptions about mental illness “running in the family” – the findings come as a timely clarification.
For decades, public awareness campaigns and even classroom teachings in Thailand have stressed the role of family history in evaluating one’s risk of developing mental illness. Popular Thai sayings often reflect this assumption, and families may avoid discussing mental health problems for fear of “damaging” the reputation of their lineage. Yet, according to the Danish researchers, 89% of individuals diagnosed with schizophrenia, and approximately 60% of those with depression, have no close relatives with these disorders. “It clearly shows that all of us have a risk of developing mental illness, not only those with an affected relative,” stated the study’s lead co-researcher (Neuroscience News).
The research used advanced linkages of Denmark’s national health and civil registers, tracing diagnoses across family generations. All data were pseudonymized, protecting personal privacy. The study examined a wide spectrum of conditions, ranging from substance abuse and schizophrenia to bipolar disorder, depression, and personality disorders—comprising over 80 million person-years of follow-up.
Key findings include that just 11% of people with schizophrenia had a close relative with the condition, and 40% of people with depression had a family history. Even in families where close relatives, such as siblings or parents, were affected, the majority of individuals—92% in the case of schizophrenia—never developed the disorder.
These figures highlight the complexity of mental illnesses. While heredity does elevate risk, most disorders emerge through a combination of many small genetic variations and environmental influences, such as stress, trauma, or substance use. “Mental disorders are hereditary, but also highly polygenic. They often result from many small genetic variations—not a single ‘disease gene’. Environment and chance play enormous roles,” explained the project’s co-author.
For Thai families, where intergenerational relationships and ancestral pride remain crucial, these findings help reduce fear and guilt. “Even with a family member affected, most people never develop a mental disorder themselves,” summarized the research team. For depression, though the lifetime risk rises to about 15% for those with an affected close relative, that still means 85% with the same family background will not develop depression.
Expert responses to the Danish data have been significant. Mental health campaigners in Thailand, including those at leading psychiatric hospitals and NGOs, highlight that this research can help to destigmatize mental illness, making it easier for Thais to seek support without fear of blame or ostracism. A leading psychiatrist from Thailand’s largest psychiatric hospital explained that “… public misconceptions linking mental illness directly to family shame or karma often increase suffering. These Danish findings support the view that mental illness should be viewed primarily as a health condition influenced by complex factors, not the result of lineage or moral failing.”
The call for a dual-track approach—combining personalized treatment with broad population-level strategies—matches the direction recommended by the Ministry of Public Health. In recent years, Thai authorities have advocated for both individualized care (considering patient history and social factors) and community campaigns addressing alcohol use, stress, and stigma. Population-wide approaches such as improving work-life balance, discouraging excessive alcohol and substance use, and resilience building in schools align closely with the Danish study’s recommendations.
Historically, Thai society has wrestled with the burden of concealment when it comes to psychiatric conditions. Ancestral records, sometimes crucial for legal or religious matters such as temple ordination, were said to “go silent” on mental health. However, increasing emphasis on transparency and education over the last two decades—evidenced by rising numbers of psychiatric consultations and mental health literacy efforts—means these findings are likely to accelerate change.
The methodology behind the Danish research was ambitious, using the country’s renowned Multigeneration Register, which connects civil records and psychiatric diagnoses back to church documents from the 1920s. By following over 3 million individuals across multiple generations, the research team was able to provide—for the first time—absolute risk numbers, not just relative probabilities. For the Thai research and clinical community, this level of precision represents an important international benchmark.
The Thai context is unique: strong family bonds, Buddhist values emphasizing compassion, and rapid urbanization all influence mental health. Experts stress that while family support can be protective, undue emphasis on heredity can delay both diagnosis and treatment for those feeling “cursed” by their family’s history. Current policies from the Ministry of Public Health and the Department of Mental Health increasingly prioritize overcoming stigma and expanding access to care across all regions, including rural provinces where resources are traditionally scarce.
Looking ahead, the research has clear implications for education, awareness, and clinical practice in Thailand. With mental health disorders projected to rise as a share of overall disease burden amid growing social and economic pressures, accurate information and non-discriminatory attitudes will be crucial. Mental health educators in Bangkok universities and provincial hospitals have already called for curriculum updates to reflect the new evidence, and for media coverage to emphasize prevention, resilience, and early intervention—not just genetics.
Practical recommendations for Thai readers include:
- Understand that anyone can experience mental health problems, regardless of family history.
- If a close relative has a mental illness, recognize that personal risk is increased, but development of the same condition is not at all inevitable.
- Focus on known protective behaviors: avoiding excessive alcohol and drugs, managing stress, seeking social support, and consulting professionals at early signs.
- Support efforts to reduce stigma, both in families and communities.
Families and individuals alike should remember that mental illness is complex—arising through a blend of genetics, life experiences, and sometimes pure chance. As the study’s co-lead author reminds us, “Heredity is unpredictable and complex. Family history plays a part, but much remains outside our control. The best protection is a caring, educated society.”
For those interested in the full academic study, it is accessible in The Lancet Psychiatry: “Absolute and relative risks of mental disorders in families: a Danish register-based study” (Lancet Psychiatry), with additional commentary and data from Aarhus University’s press releases (Aarhus University).