1. Department of Sociology and Carolina Population Center, University of North Carolina, CB#3210, Chapel Hill, NC 27599-3210, USA
2. Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
3. Department of Sociology, University of Washington, Seattle, WA, USA
4. Department of Sociology, University of Macau, Av. Padre Tomás Pereira, Taipa, Macau