Genetic and Environmental Influences on Traits of Gender Identity Disorder: A Study of Japanese Twins Across Developmental Stages

The present study examined: (1) gender and age differences of mean gender identity disorder (GID) trait scores in Japanese twins; (2) the validity of the prenatal hormone transfer theory, which predicts that, in dizygotic (DZ) twin pairs, twins with an opposite-gender co-twin more frequently exhibit...

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Bibliographic Details
Published in:Archives of sexual behavior 2016-10, Vol.45 (7), p.1681-1695
Main Authors: Sasaki, Shoko, Ozaki, Koken, Yamagata, Shinji, Takahashi, Yusuke, Shikishima, Chizuru, Kornacki, Tamara, Nonaka, Koichi, Ando, Juko
Format: Article
Language:English
Subjects:
Adolescent
Adult
Behavioral Science and Psychology
Child
Child, Preschool
Cross-Sectional Studies
Female
Gender Dysphoria - epidemiology
Gender Dysphoria - genetics
Gender identity
Heredity
Humans
Japan - epidemiology
Male
Original Paper
Psychology
Public Health
Sexual Behavior
Social Sciences
Surveys and Questionnaires
Twins
Twins, Dizygotic - genetics
Twins, Dizygotic - statistics & numerical data
Twins, Monozygotic - genetics
Twins, Monozygotic - statistics & numerical data
Young Adult
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Summary:The present study examined: (1) gender and age differences of mean gender identity disorder (GID) trait scores in Japanese twins; (2) the validity of the prenatal hormone transfer theory, which predicts that, in dizygotic (DZ) twin pairs, twins with an opposite-gender co-twin more frequently exhibit GID traits than twins with a same-gender co-twin; and (3) the magnitude of genetic and environmental influences on GID traits as a function of age and gender. Data from 1450 male twin pairs, 1882 female twin pairs, and 1022 DZ male–female pairs ranging from 3 to 26 years of age were analyzed. To quantify individual variances in GID traits, each participant completed four questionnaire items based on criteria for GID from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). Our most important findings were: (1) Japanese females exhibited GID traits more frequently than males and Japanese children exhibited GID traits less frequently than adolescents and adults (among females, the prevalence was 1.6 % in children, 10 % in adolescents, and 12 % in adults; among males, the prevalence was 0.5, 2, and 3 %, respectively); (2) the data did not support the prenatal hormone transfer theory for GID traits; and (3) a large part of the variance for GID traits in children was accounted for by familial factors; however, the magnitude was found to be greater in children than in adolescents or adults, particularly among females. This study suggests that although the prevalence is likely to increase, familial effects are likely to decrease as individuals age.
ISSN:0004-0002
1573-2800
DOI:10.1007/s10508-016-0821-4