Heritability of cannabis initiation was higher in teenagers than young adults because environmental influences grew with age
In 7,753 Dutch twins and siblings aged 11-25, cannabis initiation heritability was 40% at age 16.5, but environmental influences (shared and unique) increased with age, making genetics relatively less important in young adults.
Quick Facts
What This Study Found
Researchers examined 6,208 twins and 1,545 siblings from 3,503 Dutch families to understand how the genetic-environmental balance for cannabis initiation changed with age.
At the median age of 16.5, genetic factors explained 40% of individual differences in cannabis initiation. Twins resembled each other more than non-twin siblings, even after accounting for age differences.
Environmental influences increased with age across all categories. Factors shared only between twins accounted for 47% of variance, factors shared by all siblings in a family for 24%, and individual-specific factors for 13%. All of these environmental components grew larger as young people aged.
The result was that heritability was proportionally higher in adolescents than in young adults, not because genetic influence decreased, but because environmental exposure opportunities expanded with age.
Key Numbers
7,753 total participants from 3,503 families. At age 16.5: genetic = 40%, twin-shared environment = 47%, family-shared = 24%, unique environment = 13%. All environmental components increased with age.
How They Did This
Twin-sibling study using genetic structural equation modeling. 6,208 twins (ages 13-20) and 1,545 siblings (ages 11-25) from 3,503 families in the Netherlands Twin Register. Self-reported cannabis use from the Dutch Health Behavior Questionnaire. Age moderation of genetic and environmental variance components tested.
Why This Research Matters
The finding that environmental influences on cannabis initiation grew with age helped explain why prevention efforts targeting social environments may be increasingly important for older adolescents and young adults.
The Bigger Picture
The age-dependent shift from genetic to environmental influence suggested that cannabis initiation in older teens and young adults was increasingly driven by social context, peer groups, and availability rather than genetic predisposition.
What This Study Doesn't Tell Us
Dutch sample where cannabis is relatively accessible, potentially affecting environmental component estimates. Self-reported cannabis use. Cross-sectional age comparisons rather than longitudinal tracking.
Questions This Raises
- ?Do the same age-moderation patterns apply to progression from initiation to problematic use?
- ?Would restricting cannabis availability change the heritability estimates?
Trust & Context
- Key Stat:
- Environmental influences on cannabis initiation grew with age
- Evidence Grade:
- Large twin-sibling study with age moderation analysis providing robust estimates of how genetic and environmental influences shift across adolescence.
- Study Age:
- Published in 2011. Understanding of age-dependent heritability of substance use has continued to develop.
- Original Title:
- Age moderates non-genetic influences on the initiation of cannabis use: a twin-sibling study in Dutch adolescents and young adults.
- Published In:
- Addiction (Abingdon, England), 106(9), 1658-66 (2011)
- Authors:
- Distel, Marijn A(2), Vink, Jacqueline M(8), Bartels, Meike(3), van Beijsterveldt, Catharina E M, Neale, Michael C, Boomsma, Dorret I
- Database ID:
- RTHC-00481
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Is trying cannabis genetic or environmental?
Both, but it changes with age. At 16.5, genetics explained 40% of who tried cannabis. As people got older, environmental factors (friends, social context, availability) became increasingly important.
Why did twins resemble each other more than regular siblings?
Twins share more environmental factors (same age peers, same school classes, same social timing) than siblings born in different years. This "twin-specific" shared environment accounted for 47% of variance in cannabis initiation.
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Cite This Study
https://rethinkthc.com/research/RTHC-00481APA
Distel, Marijn A; Vink, Jacqueline M; Bartels, Meike; van Beijsterveldt, Catharina E M; Neale, Michael C; Boomsma, Dorret I. (2011). Age moderates non-genetic influences on the initiation of cannabis use: a twin-sibling study in Dutch adolescents and young adults.. Addiction (Abingdon, England), 106(9), 1658-66. https://doi.org/10.1111/j.1360-0443.2011.03465.x
MLA
Distel, Marijn A, et al. "Age moderates non-genetic influences on the initiation of cannabis use: a twin-sibling study in Dutch adolescents and young adults.." Addiction (Abingdon, 2011. https://doi.org/10.1111/j.1360-0443.2011.03465.x
RethinkTHC
RethinkTHC Research Database. "Age moderates non-genetic influences on the initiation of ca..." RTHC-00481. Retrieved from https://rethinkthc.com/research/distel-2011-age-moderates-nongenetic-influences
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.