Final answer:
The concept being described is the 'family life cycle,' a sociological model representing the predictable steps and patterns families experience over time, originally formulated by Paul Glick. Modern sociology now leans towards the 'family life course,' which views these life events as more fluid rather than in strict stages. This model accommodates changing societal norms and individual life experiences.
Step-by-step explanation:
The timetable according to which individuals are expected to accomplish life's tasks such as getting married, having children, or establishing themselves in a career is known as the family life cycle. The family life cycle is a concept developed in sociology that represents a set of predictable steps and patterns families experience over time. Traditionally, these steps were seen as occurring in strict, sequential stages, but modern sociological models, such as the family life course, view these events as more fluid and less bound to a particular sequence.
One of the foremost models of the family life cycle was developed by Paul Glick in 1955 and later elaborated by Evelyn Duvall. Glick proposed that most individuals would grow up, establish a family, rear and launch children, experience an 'empty nest' period, and eventually come to the end of their lives, with the cycle continuing with each generation. However, contemporary sociological thought has moved away from rigid stage theories to models which accommodate different life experiences such as delayed marriage, non-marital childbearing, and extended education.
These developments have led sociologists to question traditional milestones that define adulthood and consider how societal changes impact family structures and life courses. As society evolves, so too does the concept of what it means to be an adult and the timeline on which these milestones are achieved, reflecting cultural values, social norms, and individual circumstances.