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. Author manuscript; available in PMC: 2010 Mar 24.
Published in final edited form as: Addiction. 2009 Mar;104(3):430–438. doi: 10.1111/j.1360-0443.2008.02456.x

Table 2.

Percentage (%) of additive genetic variance, shared, and non-shared environmental variance in cannabis availability, cannabis initiation and the number of DSM-IV symptoms of abuse.

Cannabis Availability Cannabis Initiation DSM-IV Symptoms of Cannabis Abuse
Total genetic effects 18 27 35
 % Associated with cannabis initiation - - 62%
 % Associated with cannabis availability - 3% 2%
 Unique genetic variance - 97% 36%
Total shared environmental effects 34 42 34
 % Associated with cannabis initiation - - 4%
 % Associated with cannabis availability - 96% 92%
 Unique shared environ' variance - 4% 0%
Total non-shared environmental effects 49 32 31
 % Associated with cannabis initiation - - 82%
 % Associated with cannabis availability - 3% 3%
 Unique non-shared environ' variance - 97% 16%

1 Based on the best fitting Model 2