There is considerable evidence that the tendency to be hot tempered is familial (Lefkowitz et al., 1977; Mattes and Fink, 1987; Stewart and deBlois, 1983) and may be transmitted as a personality trait rather than as part of an associated diagnosis (Mattes and Fink, 1987). While conducting a family study of patients with temper outbursts, seven adopted patients were identified; this provided an opportunity to evaluate whether the familial transmission of temper outbursts is genetic or environmental.