Note carefully it is not just the person, not just the environment, but both in interaction. The social work world view is that people are shaped by a great range of environmental forces - family, neighborhood, larger communities, as well as public policies. These forces may open or limit resources and opportunities. They also strongly influence the person who grows and lives within them. Individual people, too, bring differences in endowment and temperament, in internal capacities and abilities, in ways of coping with challenges, which shape their inner experiences and their ability to engage with, and make use of, environmental resources.
Individuals change over the lifespan.
Individuals can also profoundly alter their environments. It is a complex enterprise of mind and heart, reflection and action. It is also enormously ambitious in scope, stretching us mere mortals to be so open, to take in so much, to be so balanced and to synthesize so much. Some say context is everything, apparently minimizing the person as agent in favor of the environment. Others emphasize the person as agent, as the living agent of experience, apparently minimizing the environment in favor of the person.