Table 1.

Sample characteristics (means or percent endorsement) as a function of family risk status for DSM-III-R alcohol dependence (AD).

Characteristic	1. Father AD (n = 334)	2. Father unaffected; MZ Co-twin AD (n = 111)	3. Father unaffected; DZ Co-twin AD (n = 89)	4. Father unaffected; Co-twin unaffected (n = 193)
# offspring, total	505	162	145	304
# siblings, mean (SD)	1.64 (1.00)	1.72 (1.11)	1.79 (1.11)	1.55 (0.94)
Child sex, % male	49.7	46.9	49.7	44.1
Child age, mean (SD)	19.91 (3.94)NS	19.98 (3.86)NS	19.25 (3.81)NS	19.62 (3.95)
Paternal age, mean (SD)	50.36 (2.61)NS	51.10 (2.68)NS	50.76 (2.60)NS	50.86 (2.65)
Maternal age, mean (SD)	47.36 (3.82)NS	47.40 (4.30)NS	47.18 (3.64)NS	48.31 (3.59)
Pregnancy risk factors:
Mother smoked during pregnancy	27.7*	24.1NS	20.0NS	18.4
Mother drank before knew pregnant	27.9*	29.0*	23.4NS	19.4
Mother drank after knew pregnant	16.6*	14.2NS	14.5NS	8.9
Sociodemographic risk/protective factors:
Paternal university education, %	58.2NS	63.6NS	71.7NS	65.1
Family income< $35,000, %	17.3*	19.8*	20.7*	10.5
Parental marital status: divorced, %	21.9*	15.4NS	15.2NS	12.2
Parental psychiatric and substance abuse histories#:
Paternal DSM-III-R substance abuse/dependence, %	17.8*	10.5*	4.8NS	2.3
Paternal DSM-III-R nicotine dependence, %	65.5*	47.5*	47.6*	22.7
Paternal any DSM-III-R psychiatric diagnosis, %	34.7*	18.5*	18.6*	8.2
Maternal DSM-IV alcohol abuse %	10.9NS	6.2NS	9.0NS	7.2
Maternal DSM-IV AD, %	11.7NS	12.3NS	6.9NS	6.9
Maternal history of DSM-IV ADHD, %	8.5NS	7.4NS	7.6NS	4.3

^*p < 0.05 for comparison with control group (father unaffected, cotwin unaffected).

^N.S.Non-significant for comparison with control group (father unaffected, cotwin unaffected); all comparisons adjusted for non-independence of observations (multiple siblings per family).

^#Maternal diagnosis of nicotine dependence and paternal ADHD were not available.