Table 2.

Variance components (standardized) in the Parental Monitoring and Drug Initiation items attributed to additive genetic (A), shared environment (C), and non-shared environmental (E) effects along with their 95% confidence intervals.

Items	A	C	E
1. Parents knowledge of child’s friends	0.17 (0.00–0.51)	0.30 (0.00–0.50)	0.53 (0.43–0.63)
2. Parents knowledge of how child spent their money	0.31 (0.00–0.54)	0.14 (0.00–0.43)	0.55 (0.46–0.65)
3. Parents knowledge of how child spent their free time	0.17 (0.00–0.49)	0.30 (0.00–0.49)	0.53 (0.44–0.64)
4. Cannabis initiation	0.42 (0.25–0.60)	0.33 (0.16–0.49)	0.25 (0.21–0.30)
5. Stimulants initiation	0.57 (0.26–0.74)	0.09 (0.00–0.36)	0.34 (0.26–0.43)
6. Cocaine initiation	0.64 (0.34–0.79)	0.08 (0.00–0.35)	0.28 (0.21–0.36)