Measures of alcohol consumption and problems are described in detail in (Dick et al. 2011). Briefly, consumption measures included: Frequency (how often do you drink alcohol at all?), Frequency × Quantity (the frequency of reported use in the past 28 days multiplied by the quantity of drinks consumed per drinking day during the past 28 days; drinks defined as 1 beer, 1 glass of wine, or 1 mixed drink containing hard liquor equivalent to 10 grams of ethanol), Frequency of Heavy Drinking (at the present, how often do you within one occasion consume more than five bottles of beer, or more than a bottle of wine, or more than half a bottle of hard liquor?), Frequency of Intoxication (how often do you use alcohol to get drunk?), and Max Drinks (the maximum number of drinks twins reported ever consuming in a 24 hour period). Alcohol problem measures included: The Mälmö-modified MAST (Mm-MAST;(17)), a 9-item self-report scale of drinking patterns and problems designed for application in Nordic cultures (18)) and the 22 items from the Rutgers Alcohol Problem Index (RAPI)(19), a
