Cannabis use and cannabis-use disorder are not the same outcome. Twin studies suggest heritable influences, while access, age, context and exposure remain essential.
Quick answer
What does the evidence support?
Twin research supports both genetic and environmental contributions to cannabis use and problematic use. Research does not support using family or twin status to predict an individual’s response to cannabis.
Key takeaways
- Twin research supports both genetic and environmental contributions to cannabis use and problematic use.
- Trying cannabis and developing a use disorder are different outcomes.
- Age of exposure, availability and social context affect who is exposed and how use develops.
- Research does not support using family or twin status to predict an individual’s response to cannabis.
Use is not dependence
Some twin studies examine whether someone has ever used cannabis, while others examine frequent use, symptoms or disorder. Combining these outcomes can exaggerate what a specific study actually found.
Genetic and environmental components
Twin models generally support heritable contributions to cannabis-related outcomes alongside shared and non-shared environmental effects. The size of those components changes across cohorts and definitions.
Context changes exposure
Policy, availability, peer use, age and social norms can change the probability of exposure. That means genetic liability is expressed within a changing environment rather than in isolation.
TwinPare boundary
TwinPare Research does not recommend cannabis use, estimate personal addiction risk or provide instructions for treating cannabis-use disorder.
Source notes
The source has been verified and editorially reviewed for this article. The limitations below show which level of conclusion the sources support.
- [cannabis-twin-review] The genetic aetiology of cannabis use: from twin models to genome-wide association studies and beyond Karin J H Verweij; Jacqueline M Vink; Abdel Abdellaoui; Nathan A Gillespie; Eske M Derks; Jorien L Treur. Translational Psychiatry, 2022. Evidence type: Review of twin and genomic research on cannabis use phenotypes Limitation: Modern review spanning twin and genomic cannabis research. Cannabis use and cannabis-use disorder are distinct phenotypes; heritability estimates vary by severity and molecular studies explain only part of twin-based heritability. PubMed
Editorial source review
This section shows how the article's key factual claims are linked to the source.
Phrasings that require caution
- Do not convert population heritability into an individual risk percentage.
- Do not describe genes as destiny or protection.
- Do not give detoxification, withdrawal-management, medication or treatment instructions.
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