We review evidence that genetic factors play no less important a role in the etiology of alcoholism in women than in men. Potential mediators of this genetic influence (differences in personality or alcohol sensitivity) exhibit equal heritability in men and women. Genetically determined differences in alcohol preference (or consumption level), a phenotype widely used in animal models of alcoholism, have been neglected as a mechanism of alcoholism inheritance. Using data from the 1992-3 interview survey of the Australian twin panel (N = 5995 twins), we have reexamined the mediating role of personality and alcohol consumption variables. By comparing the non-alcoholic co-twins of alcoholic twins, and twins from concordant unaffected pairs (separately for MZ and DZ pairs), we have avoided the problem of obtaining consumption and personality assessments that are contaminated by history of alcoholism. In MZ pairs, in both genders, co-twin's heavy alcohol exposure (drinking 5+ drinks in one day) and co-twin's Novelty Seeking score, are both predictive of alcoholism in the respondent. The effect of co-twin's heavy alcohol exposure remains significant even when the respondent's personality variables are controlled for, implying that there are genetic effects on alcoholism risk mediated through consumption pattern that are independent of those mediated through personality differences.