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. Author manuscript; available in PMC: 2009 Mar 9.
Published in final edited form as: Addiction. 2008 Jun;103(6):990–997. doi: 10.1111/j.1360-0443.2008.02210.x

Table 1.

Characteristics of 819 offspring of twins. NOTE: All values are percentages unless otherwise indicated.

Cannabis abuse or dependence
All Men Women
Offspring variables Yes (n=188) No (n=631) p-value Yes (n=118) No (n=307) p-value Yes (n=70) No (n=324) p-value
 Physical abuse 15.96 11.89 .164 17.80 14.01 .324 12.86 9.88 .460
 Sexual abuse 15.96 6.34 <.001 10.17 0.98 <.001 25.71 11.42 .003
 Mean age at interview (SD) 23.35 (3.59) 22.43 (4.67) .013 23.69 (3.43) 22.31 (4.70) .001 22.79 (3.81) 22.54 (4.60) .655
 Family income <40 K/year 37.77 35.78 .654 37.29 36.18 .842 38.57 35.40 .631
 Four group paternal drug dependence design1
  Group 1: HGHE 72.34 59.43 .019 69.49 60.59 .083 77.14 58.33 .017
  Group 2: HGLE 7.98 8.40 11.02 8.14 2.86 8.64
  Group 3: MGLE 6.38 9.51 4.24 10.42 10.00 8.64
  Group 4: LGLE 13.30 22.66 15.25 20.85 10.00 24.38
 Alcohol abuse or dependence 69.15 24.09 <.001 73.73 29.32 <.001 61.43 19.14 <.001
 Nicotine dependence 30.81 7.51 <.001 30.77 8.22 <.001 30.88 6.83 <.001
 Other illicit drug abuse or dependence 43.62 1.74 <.001 44.92 1.63 <.001 41.43 1.85 <.001
 Conduct disorder2 45.74 8.40 <.001 56.78 14.98 <.001 27.14 2.16 <.001
 Major depression 18.09 10.46 .006 15.25 7.82 .022 22.86 12.96 .034
Paternal lifetime psychiatric diagnostic variables
 Alcohol abuse or dependence 71.28 65.98 .216 67.80 67.10 .896 77.14 64.91 .068
 Nicotine dependence 67.02 56.10 .013 66.95 54.07 .021 67.14 58.02 .164
 Antisocial personality disorder 11.17 5.10 .009 8.47 3.92 .105 15.71 6.21 .010
 Major depression 17.02 15.92 .740 19.93 19.49 .924 12.86 12.11 .865
Maternal lifetime psychiatric diagnostic variables
 Maternal data missing3 19.68 20.13 .902 20.34 18.57 .690 18.57 21.60 .589
 Alcohol abuse or dependence 16.04 16.32 .873 11.86 17.43 .163 23.19 15.26 .078
 Regular smoking4 43.62 41.52 .641 40.68 42.67 .723 48.57 40.43 .224
 Drug abuse or dependence 12.23 9.98 .381 12.71 11.07 .620 11.43 8.95 .509
 Conduct disorder 11.17 6.02 .021 10.17 6.51 .211 12.86 5.56 .014
 Major depression 22.28 17.45 .190 16.52 17.67 .801 31.88 17.24 .003
1

HGHE: High genetic and low environmental risk; HGLE: High genetic and low environmental risk; MGLE: Medium genetic and low environmental risk; LGLE: Low genetic and low environmental risk

2

Three or more conduct disorder symptoms

3

Maternal data were only available for 655 offspring: 151 with and 504 without CAD.

4

100 or more cigarettes