Personality a particular pattern of behaviour and thinking prevailing across time and situations that differentiates one person from another. Must avoid nominal fallacy false belief that causes of even are explained by simply naming/identifying them. Human reproduction reshuffles genes in each generation, making unlikely that specific set of genes related to personality type would be passed on. Most behavioural scientists agree personality differences relate to impact of environmental. Personality trait - an enduring personal characteristic that reveals itself in a particular pattern of behaviour in a variety of situations. People differ along a wide range of values. Once personality traits developed, they reside in brain if personality traits changed through learning, those changes must have neurological basis in brain factors. 1 people with particular trait react similarly across situations b/c they experience unique sense of similarity across those situations that guide their feelings, thoughts, and behaviour not all traits have equal influence on their possessors.