Psychiatry Research 120 (2003) 61–69 0165-1781/03/$ - see front matter  2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0165-1781Ž03.00172-0 Exposure to traumatic events and experiences: aetiological relationships with personality function Kerry L. Jang *, Murray B. Stein , Steven Taylor , Gordon J.G. Asmundson , a, b a c W. John Livesley a Division of Behavioural Science, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, a BC, Canada V6T 2A1 Anxiety & Traumatic Stress Disorders Program, Department of Psychiatry (0985), University of California, San Diego, La Jolla, b CA 92093-0985, USA Anxiety and Illness Behavior Laboratory, Faculty of Kinesiology and Health Studies, University of Regina, Regina, SK, c Canada S4S 0A2 Received 25 October 2002; received in revised form 23 May 2003; accepted 16 June 2003 Abstract Empirical research has shown that the odds of experiencing traumatic events are influenced by genetic factors and the heritability of trauma exposure varies with the type of trauma. Traumatic events per se are unlikely to be heritable; more likely to be inherited are factors such as personality that influence the person’s risk for entering into, or creating, potentially hazardous situations. With data from 406 twin pairs (222 monozygotic and 184 dizygotic twin pairs) from the urban general population, the present study used multiple regression analysis to identify personality variables associated with exposure to trauma, and estimated the degree to which these relationships were mediated by genetic factors. The experience of violent assaultive traumatic events was predicted by antisocial personality traits, specifically juvenile antisocial behavior, self-harming behavior, Psychoticism (e.g. adult antisocial behavior and substance misuse), and being open to new ideas and experiences. Genetic factors were found to partially mediate these relationships as indexed by the genetic correlation coefficient. The values of the genetic correlations were statistically significant and ranged from 0.14 to 0.36, accounting for 5–11% of the observed correlation between personality and trauma exposure. These findings suggest that heritable personality characteristics explain part of the variance in the likelihood of exposure to some classes of traumatic events.  2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Twins; Posttraumatic stress disorder; Trauma; Genetics; Personality disorder 1. Introduction Twin studies of posttraumatic stress disorder (PTSD) reveal that the symptoms of this disorder *Corresponding author. Tel.: q1-604-822-7895; fax: q1- 604-822-7756. E-mail address: kjang@unixg.ubc.ca (K.L. Jang). are moderately heritable. For identical and fraternal male twins who had experienced combat, genetic factors accounted for approximately 30% of the total variance in symptoms (True et al., 1993). Similarly, genetic factors accounted for 26–36% in the variance of PTSD symptoms in a predomi- nantly female sample of twins from the general population (Stein et al., 2002).