1. Department of Sociology and Institute of Behavioral Science, University of Colorado, Boulder, CO 80309-0327, USA
2. Departments of Political Science, Microbiology, and Biochemistry, 215 Pond Lad, The Pennsylvania State University, University Park, PA 16802, USA
3. Midwest Alcoholism Research Center, Washington University, St. Louis, MO, USA
4. Virginia Institute for Psychiatric and Behavioral Genetics, Medical College of Virginia, Richmond, VA, USA