Molecular genetics, aging, and well-being: Sensitive period, accumulation, and pathway models

Aging reflects ongoing transactions between context and person across many decades of life. Life course sociology is now central to investigations focused on the dynamic social context of aging, with its distinctive emphasis on long-term patterns in people's statuses, roles, and relationships. Recent advances in the understanding of the genome and its measurement have created new and exciting possibilities for studying the genetic basis of aging-related outcomes. The relationship between context and genetic factors may often be transactional, with influences extending reciprocally among environmental factors and genetic processes. This chapter reviews studies that suggest links between social and molecular processes extending across the phases of life. Very few empirical studies of aging draw upon both the life course and molecular genetics, but there is a rapidly growing number of studies from each perspective that suggest points of intersection. It emphasizes studies of health, broadly defined as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity," because many gene-environment studies focus on indicators of physical and mental well-being. Despite the growing relevance of molecular genetics to studies of life course sociology and aging, several cautionary points are appropriate. Epigenetic mechanisms could provide insight into vulnerable windows very early in life that then have long-term implications for health and well-being. Behavioral studies of aging that are informed by molecular genetics present exciting challenges to the technical and creative skills of a new generation of scientists.