The Genetic Structure of Cloninger’s Seven-Factor Model of Temperament and Character in a Japanese Sample Juko Ando Keio University, Faculty of Letters, Department of Education, Tokyo Yutaka Ono Keio University, Health Center, Kanagawa Kimio Yoshimura Cancer Information and Epidemiology Division, National Cancer Center Research Institute, Tokyo Naoko Onoda Keio University, School of Medicine, Tokyo Manabu Shinohara Shigenobu Kanba Department of Psychiatry, Yamanashi Medical University Masahiro Asai Keio University, School of Medicine, Tokyo ABSTRACT Theoretical assumptions regarding the genetic and environ- mental structure of personality proposed in Cloninger’s seven-factor model of Journal of Personality 70:5, October 2002. Copyright # 2002 by Blackwell Publishing, 350 Main Street, Malden, MA 02148, USA, and 208 Cowley Road, Oxford, OX4 1JF, UK. Correspondence regarding this article may be directed to Juko Ando, Keio University, Faculty of Letters, 2-15-45 Mita, Minato-Ku, Tokyo 108-8345 Japan. Telephone: 81-3-3453-4511. E-mail: juko@msa.biglobe.ne.jp.