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Two Cohort and Three Independent Anonymous Twin Projects at the Keio Twin Research Center (KoTReC)

  • Juko Ando (a1), Keiko K. Fujisawa (a1), Chizuru Shikishima (a2), Kai Hiraishi (a3), Mari Nozaki (a4), Shinji Yamagata (a5), Yusuke Takahashi (a6), Koken Ozaki (a7), Kunitake Suzuki (a8), Minako Deno (a9), Shoko Sasaki (a4), Tatsushi Toda (a10), Kazuhiro Kobayashi (a10), Yutaro Sugimoto (a1), Mitsuhiro Okada (a1), Nobuhiko Kijima (a11), Yutaka Ono (a12), Kimio Yoshimura (a13), Shinichiro Kakihana (a14), Hiroko Maekawa (a15), Toshimitsu Kamakura (a16), Koichi Nonaka (a17), Noriko Kato (a18) and Syuichi Ooki (a19)...


The Keio Twin Research Center has conducted two longitudinal twin cohort projects and has collected three independent and anonymous twin data sets for studies of phenotypes related to psychological, socio-economic, and mental health factors. The Keio Twin Study has examined adolescent and adult cohorts, with a total of over 2,400 pairs of twins and their parents. DNA samples are available for approximately 600 of these twin pairs. The Tokyo Twin Cohort Project has followed a total of 1,600 twin pairs from infancy to early childhood. The large-scale cross-sectional twin study (CROSS) has collected data from over 4,000 twin pairs, from 3 to 26 years of age, and from two high school twin cohorts containing a total of 1,000 pairs of twins. These data sets of anonymous twin studies have mainly targeted academic performance, attitude, and social environment. The present article introduces the research designs and major findings of our center, such as genetic structures of cognitive abilities, personality traits, and academic performances, developmental effects of genes and environment on attitude, socio-cognitive ability and parenting, genes x environment interaction on attitude and conduct problem, and statistical methodological challenges and so on. We discuss the challenges in conducting twin research in Japan.

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Corresponding author

address for correspondence: Juko Ando, Faculty of Letters, Keio University, Tokyo, Japan. E-mail:


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