. Author manuscript; available in PMC: 2013 May 1.

Published in final edited form as: Behav Genet. 2011 Oct 30;42(3):345–353. doi: 10.1007/s10519-011-9516-8

Table 3.

Age-corrected cross-twin, within-trait correlations for lifetime substance use and family environment variables

	Smoking	Alcohol	Marijuana	Cocaine	Stimulant	Sedative	Hallucinogen	Any illicit drug	Parental attitudes	Household use
MZ	0.41	0.44	0.58	0.58	0.46	0.34	0.48	0.59	0.34	0.75
DZ	0.21	0.42	0.30	0.29	0.23	0.19	0.28	0.32	0.24	0.72

MZ monozygotic twins, DZ dizygotic twins