Personal health reflects harmony between individual and experience; it is optimal homeostasis. Disease is an outcome of incongruity leading to dishomeostasis. Relative to earlier times, disease in modern society has higher "heritability" (in the broad meaning of the term). Inherited risks are facts compatible with anticipation and prevention of disease. This viewpoint has major implications for medical practice, deployment of health services, themes of research, and education of health care personnel and citizens.