Reciprocal Determinism
Reciprocal determinism is Bandura's theory explaining how personality develops through a three-way relationship. Your personality traits draw you toward certain environments, and those environments then strengthen those traits through reinforcement.
This creates a continuous cycle where your personal factors, behaviors, and environment all influence each other. For example, if you're naturally creative, you might join an art club, which then further develops your creativity.
The three components—person/cognitive factors, behavior, and environment—work together in a triangle of influence, constantly shaping and reshaping your personality.