We propose to conduct a multifactorial genetic study of cancer risk-related behaviors and other complex human characteristics. The main areas of interest are tobacco smoking, excess alcohol consumption, psychological traits, and HIV/AIDS susceptibility and progression. The subjects will be adult male and female probands who display one or more of the phenotypes of interest together with their brothers, sisters and parents. Information on tobacco and alcohol use, psychological and personality traits, sexual behavior, HIV status and progression, and other characteristics with possible genetic components will be obtained through structured interviews and questionnaires. DNA will be prepared from blood samples and typed for a series of candidate genes chosen for function and for random polymorphic markers. By correlating the genotypic and phenotypic information, we hope to identify individual loci that interactively contribute to many different aspects of human health and disease.