had never become dependent on or abused alcohol, nicotine or other illicit substances (see Supplemental Table S1). Additionally, controls were also screened to exclude individuals with major axis I disorders, including schizophrenia, mood disorders, and anxiety disorders. More demographic data were available in the Supplemental Table S1 or elsewhere [Bierut et al., 2010; Edenberg et al., 2005; Edenberg et al., 2010; Zuo et al., 2011a; Zuo et al., 2011b]. All subjects gave written informed consent to participating in protocols approved by the relevant institutional review boards and were de-identified in this study.
