The innate characteristics of a person that influence their behavior are grouped under the term temperament. Gordon Allport, in his groundbreaking work dating from 1937, highlighted the interconnection between an individual’s temperament and their emotions, mood, and reactivity, thus emphasizing the inherited aspect of temperament. According to Sonia Capelli and Agnès Helme-Guizon, Allport follows in the tradition of Greek thought, considering temperament, like physical appearance or intelligence, to be a fundamental component that shapes personality. His view of temperament is deeply rooted in a psychobiological approach, viewing it as an intrinsic resource of the individual, comparable to their physical abilities. He therefore argues that the behavioral manifestations of temperament appear from a very young age.