Personality: What defines us and why. How do we differ in personality, how do such differences arise, and what role do genes and environment play in this? This non-fiction book provides a well-founded, up-to-date overview of the current state of psychological research on these questions. Jens Asendorpf, one of the most renowned personality psychologists of our time, covers a wide range of topics. How does personality manifest in behavior and social relationships, can we trust personality assessments, what are the "Big Five"? Can personality be inferred from traces on the internet, and how can emotional and social competencies be tested? How much does personality change over the course of life, and what do personality differences among children indicate about later differences in adulthood? To what extent is our personality changeable?.