Table 5.
Genetic and environmental contributions to lifetime substance use
| Substance | % Variancea (95% CI) |
% of C variance in substance use accounted for by household use | % of C variance in substance use accounted for by parental attitudes | % of Total C variance in substance use accounted for by family environment (95% CI) | ||
|---|---|---|---|---|---|---|
| a2 | c2 | e2 | ||||
| Smoking | 62 (12; 83) | 10 (0; 56) | 27 (17; 40) | 13 | 10 | 23 (0;100) |
| Alcohol | 11 (0; 56) | 62 (19; 82) | 26 (15; 42) | 5 | 9 | 14 (0;100) |
| Marijuana | 42 (11; 75) | 36 (5; 63) | 22 (16; 31) | 19 | 11 | 30 (2; 100) |
| Cocaine | 47 (18; 76) | 31 (6; 58) | 21 (14; 31) | 10 | 90 | 100 (11;100) |
| Stimulant | 54 (22; 73) | 12 (0; 40) | 34 (23; 46) | 25 | 75 | 100 (2; 100) |
| Sedative | 41 (1; 69) | 16 (0; 54) | 42 (29; 60) | 13 | 73 | 87 (0; 100) |
| Hallucinogen | 43 (6; 80) | 29 (0; 61) | 28 (18; 40) | 7 | 3 | 10 (0;100) |
| Any illicit drug | 41 (10; 75) | 37 (5; 64) | 22 (15; 30) | 27 | 17 | 44 (7; 100) |
a2 additive genetic variance for substance, c2 shared environmental variance for substance, e2 unique environmental variance for substance. The % of C variance columns represent the proportion of shared environmental variance in lifetime substance use that is accounted for by household substance use, parental attitudes, and the total percent accounted for by both family environmental variables. 95% CI 95% confidence intervals for % C variance accounted for by family environment
a
Proportion of total genetic and environmental variance for each substance from trivariate Cholesky. Sums 100% allowing for rounding error