A new study has found that individuals with ADHD have a higher risk of being convicted of a crime, and reveals this connection also extends to their family members. The research suggests that shared genetics are a meaningful part of the explanation for this link. Published in Biological Psychology, the findings show that the risk of a criminal conviction increases with the degree of genetic relatedness to a relative with ADHD.
The connection between ADHD and an increased likelihood of criminal activity is well-documented. Past research indicates that individuals with ADHD are two to three times more likely to be arrested or convicted of a crime. Scientists have also established that both ADHD and criminality have substantial genetic influences, with heritability estimates around 70-80% for ADHD and approximately 50% for criminal behavior. This overlap led researchers to hypothesize that shared genetic factors might partly explain the association between the two.
While some previous studies hinted at a familial connection, they were often limited to specific types of crime or a small number of relative types. The current research aimed to provide a more complete picture. The investigators sought to understand how the risk for criminal convictions co-aggregates, or clusters, within families across a wide spectrum of relationships, from identical twins to cousins. They also wanted to examine potential differences in these patterns between men and women.
“ADHD is linked to higher rates of crime, but it’s unclear why. We studied families to see whether shared genetic or environmental factors explain this connection, aiming to better understand how early support could reduce risk,” said study author Sofi Oskarsson, a researcher and senior lecturer in criminology at Örebro University.
To conduct the investigation, researchers utilized Sweden’s comprehensive national population registers. They analyzed data from a cohort of over 1.5 million individuals born in Sweden between 1987 and 2002. ADHD cases were identified through clinical diagnoses or prescriptions for ADHD medication recorded in national health registers. Information on criminal convictions for any crime, violent crime, or non-violent crime was obtained from the National Crime Register, with the analysis beginning from an individual’s 15th birthday, the age of criminal responsibility in Sweden.
The study design allowed researchers to estimate the risk of a criminal conviction for an individual based on whether a relative had ADHD. By comparing these risks across different types of relatives who share varying amounts of genetic material—identical twins (100%), fraternal twins and full siblings (average 50%), half-siblings (average 25%), and cousins (average 12.5%)—the team could infer the potential role of shared genes and environments.
The results first confirmed that individuals with an ADHD diagnosis had a substantially higher risk of being convicted of a crime compared to those without ADHD. The risk was particularly elevated for violent crimes.
The analysis also revealed a significant gender difference: while men with ADHD had higher absolute numbers of convictions, women with ADHD had a greater relative increase in risk compared to women without the disorder. For violent crime, the risk was over eight times higher for women with ADHD, while it was about five times higher for men with ADHD.
“Perhaps not a surprise given what we know today about ADHD, but the stronger associations found among women were very interesting and important,” Oskarsson told PsyPost. “ADHD is not diagnosed as often in females (or is mischaracterized), so the higher relative risk in women suggest that when ADHD is present, it may reflect a more severe or concentrated set of risk factors.”
The central finding of the study was the clear pattern of familial co-aggregation. Having a relative with ADHD was associated with an increased personal risk for a criminal conviction. This risk followed a gradient based on genetic relatedness.
The highest risk was observed in individuals whose identical twin had ADHD, followed by fraternal twins and full siblings. The risk was progressively lower for half-siblings and cousins. This pattern, where the association weakens as genetic similarity decreases, points toward the influence of shared genetic factors.
“Close relatives of people with ADHD were much more likely to have criminal convictions, especially twins, supporting a genetic contribution,” Oskarsson explained. “But the link is not deterministic, most individuals with ADHD or affected relatives are not convicted, emphasizing shared risk, not inevitability.”
The study also found that the stronger relative risk for women was not limited to individuals with ADHD. A similar pattern appeared in some familial relationships, specifically among full siblings and full cousins, where the association between a relative’s ADHD and a woman’s conviction risk was stronger than for men. This suggests that the biological and environmental mechanisms connecting ADHD and crime may operate differently depending on sex.
“People with ADHD are at a higher risk of criminality, but this risk also extend to their relatives,” Oskarsson said. “This pattern suggest that some of the link between ADHD and crime stems from shared genetic and/or environmental factors. Importantly, this does not mean that ADHD causes crime, but that the two share underlying vulnerabilities. Recognizing and addressing ADHD early, especially in families, could reduce downstream risks and improve outcomes.”
As with any study, the researchers acknowledge some limitations. The study’s reliance on official medical records may primarily capture more severe cases of ADHD, and conviction data does not account for all criminal behavior. Because the data comes from Sweden, a country with universal healthcare, the findings may not be directly generalizable to countries with different social or legal systems. The authors also note that the large number of statistical comparisons means the overall consistency of the patterns is more important than any single result.
Future research could explore these associations in different cultural and national contexts to see if the patterns hold. Further investigation is also needed to identify the specific genetic and environmental pathways that contribute to the shared risk between ADHD and criminal convictions. These findings could help inform risk assessment and prevention efforts, but the authors caution that such knowledge must be applied carefully to avoid stigmatization.
“I want to know more about why ADHD and criminality are connected, which symptoms or circumstances matter most, and whether early support for individuals and families can help break that link,” Oskarsson added. “This study underscores the importance of viewing ADHD within a broader family and societal context. Early support for ADHD doesn’t just help the individual, it can have ripple effects that extend across families and communities.”
The study, “The Familial Co-Aggregation of ADHD and Criminal Convictions: A Register-Based Cohort Study,” was authored by Sofi Oskarsson, Ralf Kuja-Halkola, Anneli Andersson, Catherine Tuvblad, Isabell Brikell, Brian D’Onofrio, Zheng Chang, and Henrik Larsson.
