Table 3. Heritability estimates and significance of covariates.

Phenotype	h2	se(h2)	h2 p-value	sex p-value	1930-1949 cohort p-value	1950-1969 cohort p-value	≥1970 cohort p-value	r2
DSM-IV alcohol dependence	0.61	0.08	2.8 × 10−17	1.6 × 10−24	2.7 × 10−3	1.4 × 10−9	2.4 × 10−10	0.07
Withdrawal	0.49	0.08	1.5 × 10−11	5.2 × 10−11	0.36	0.03	0.28	0.05
Gave up activities to drink	0.50	0.08	6.1 × 10−14	1.3 × 10−10	0.11	4.2 × 10−4	0.77	0.06
Time spent obtaining/using or recovering from alcohol	0.41	0.07	2.4 × 10−12	3.7 × 10−12	0.50	1.1 × 10−4	0.39	0.05
Use despite physical/psychological problems	0.51	0.07	7.8 × 10−17	2.3 × 10−14	0.03	4.1 × 10−7	0.05	0.08
Persistent desire to cut down, or inability to do so	0.47	0.06	3.8 × 10−17	5.8 × 10−16	0.04	0.04	0.07	0.04
Tolerance	0.29	0.06	6.7 × 10−9	1.0 × 10−24	9.1 × 10−3	8.2 × 10−9	2.7 × 10−8	0.05
Drink more than intended	0.59	0.09	1.8 × 10−18	1.2 × 10−14	8.7 × 10−6	5.6 × 10−16	5.3 × 10−5	0.06
Probability of assignment to low risk latent class	0.34	0.04	2.1 × 10−31	0.09	6.7 × 10−5	1.4 × 10−16	3.0 × 10−3	0.08
Membership in low risk latent class	0.52	0.06	4.4 × 10−25	1.9 × 10−17	6.7 × 10−4	7.9 × 10−13	4.2 × 10−3	0.06
Probability of assignment to moderate risk latent class	0.12	0.03	2.0 × 10−7	1.1 × 10−5	2.6 × 10−3	1.7 × 10−6	6.2 × 10−3	0.02
Membership in moderate risk latent class	0.17	0.03	1.8 × 10−5	3.3 × 10−5	0.03	1.9 × 10−4	0.025	0.01
Probability of assignment to high risk class latent class	0.19	0.03	2.9 × 10−18	1.2 × 10−14	0.24	8.8 × 10−6	0.58	0.07
Membership in high risk latent class	0.53	0.08	3.5 × 10−15	3.5 × 10−12	0.11	9.9 × 10−5	0.72	0.07

Sex and birth cohort were included as covariates in all analyses, with <1930 as the reference cohort. r²=proportion of variance accounted for by the covariates. Significant heritabilities (p<0.05) are bolded.