Suicide and suicidal behaviour remain major global health concerns. Every year, hundreds of thousands of people die by suicide worldwide, and millions more experience suicidal thoughts or attempt suicide. While prevention efforts have improved in recent decades, understanding why some individuals are more vulnerable than others remains a critical challenge for researchers and clinicians.
One striking pattern consistently observed in suicide research is the difference between males and females. Men die by suicide more frequently, yet women attempt suicide more often. Scientists have long tried to understand what drives this difference. Are genetics responsible, or do environmental and social factors play a larger role?
A large population based study conducted in Sweden has provided new insights into how genetics, family history, and sex differences influence suicide attempts. The research analysed health and family data from more than three million people, offering one of the most comprehensive investigations into this topic to date.
Suicide is responsible for around 700,000 deaths globally each year. In addition to these tragic losses, suicide attempts are far more common. Previous research suggests that roughly 2.7 percent to 3.3 percent of people will attempt suicide at some point in their lives.
However, the distribution of suicidal behaviour differs between sexes. Men have higher rates of suicide deaths, but women are approximately twice as likely to attempt suicide. These patterns have been observed across many countries and cultures.
Researchers have proposed several explanations for this gap. Possible contributing factors include:
Even with these explanations, a significant portion of the sex difference remains unexplained. This led researchers to investigate whether genetic factors might help clarify the pattern.
To better understand the genetic and familial aspects of suicide attempts, researchers analysed data from Swedish national health registers. These registers track medical diagnoses, hospital visits, deaths, and family relationships across the entire population.
The study included over 3.05 million individuals born in Sweden between 1963 and 1998. Participants were followed from age 10 until the end of 2019.
Researchers used medical records and cause of death data to identify suicide attempts. The definition included cases involving intentional self harm, severe self injury requiring hospital treatment, or suicide related deaths.
The dataset allowed investigators to examine patterns within families, including:
By comparing these groups, researchers could estimate both familial risk and the genetic contribution to suicidal behaviour.
Within the cohort, nearly 89,300 individuals had at least one suicide attempt. Overall prevalence in the population was about 2.9 percent.
The study confirmed a clear sex difference in attempts:
Although the difference may appear modest, it represents thousands of additional cases and aligns with patterns seen in other countries.
The findings also showed that people who attempted suicide were far more likely to have a diagnosed psychiatric condition. Around 75.6 percent of individuals with a suicide attempt had at least one psychiatric diagnosis, compared with only 15.2 percent among those without an attempt.
Common conditions linked with suicide attempts included:
One of the strongest findings in the study was the presence of familial aggregation. This means that suicide attempts were more common among people who had relatives with a history of suicidal behaviour.
The risk was especially high among close relatives.
For example, the likelihood of attempting suicide was significantly higher when:
Risk estimates ranged from about 1.6 to 3.4 times higher, depending on the type of family relationship.
The pattern also showed that first degree relatives, such as parents and siblings, had stronger associations than second degree relatives such as half siblings. This pattern suggests that genetics may play a role because close relatives share more genetic material.
Interestingly, the study found that familial patterns were stronger among women than men.
For example, female sibling pairs showed particularly high risk. When one sister had attempted suicide, the other sister had a much higher probability of also experiencing an attempt.
Similarly, mother daughter pairs showed stronger associations than father son pairs.
Another important finding was that same sex relatives showed stronger risk patterns than opposite sex relatives. In other words, sisters influenced sisters more strongly than sisters influenced brothers.
Researchers believe this pattern may reflect a mixture of biological, social, and environmental factors.
Possible explanations include:
Using statistical genetic models, the researchers estimated that about 42 percent of the risk for suicide attempts could be attributed to genetic factors.
This level of heritability is considered moderate and is consistent with previous twin studies.
However, the study also found something important. Genetic influence was very similar in men and women.
Estimated heritability was:
The difference between sexes was not statistically significant.
This means that genetics alone cannot explain why women attempt suicide more often than men.
The researchers also examined how suicide attempts were genetically related to other psychiatric conditions.
They found strong genetic overlap with several disorders, particularly:
The strongest genetic correlation was observed with substance use disorders, suggesting shared biological pathways.
These findings reinforce the importance of treating mental health conditions as part of suicide prevention strategies.
Because genetic risk was similar across sexes, the researchers concluded that environmental and social influences likely play a major role in the observed sex differences.
These influences may include:
Future research may focus on how these environmental influences interact with genetic vulnerability.
This concept, often called gene environment interaction, is increasingly recognised as an important component of mental health research.
The findings have important implications for clinical practice and public health.
First, family history should be taken seriously when assessing suicide risk. Individuals with relatives who attempted suicide may benefit from closer monitoring and support.
Second, clinicians may need to consider sex specific patterns in family history. For example, a woman whose mother or sister attempted suicide may face elevated risk.
Finally, the results highlight that suicide prevention requires a holistic approach that integrates genetics, mental health care, and social support systems.
Prevention strategies may include:
The Swedish cohort study provides one of the clearest pictures yet of how genetics and family history influence suicide attempts. While genetic vulnerability plays an important role, it does not fully explain the differences between men and women.
Instead, suicidal behaviour appears to result from a complex interaction between biological risk factors and environmental experiences. Understanding these interactions will be essential for developing more effective prevention strategies in the future.
Continued research combining genetics, psychology, and social science may ultimately help identify those at greatest risk and provide earlier, more targeted support.
This article is for educational and informational purposes only and does not constitute medical or mental health advice. If you or someone you know is experiencing suicidal thoughts or emotional distress, please seek help from a qualified healthcare professional or contact a local mental health support service immediately. Research findings summarized here reflect population level data and should not be used to predict individual risk.
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