title: The Relationship between the Second-to-Fourth Digit Ratio and Behavioral Sexual Dimorphism in School-Aged Children.
abstract: Sexually dimorphic brain development and behavior are known to be influenced by sex hormones exposure in prenatal periods. On the other hand, second-to forth digit ratio (2D/4D) has been used as an indirect method to investigate the putative effects of prenatal exposure to androgen. In the present study, we herein investigated the relationship between gender-role play behavior and the second-to-fourth digit ratio (2D/4D), which has been used as an indirect method to investigate the putative effects of prenatal exposure to androgens, in school-aged children. Among 4981 children who became 8 years old by November 2014 and were contactable for this survey by The Hokkaido Study of Environment and Children's Health, 1631 (32.7%), who had data for 2D/4D and Pre-school Activities Inventory (PSAI) as well as data for the survey at baseline, were available for analysis. Parents sent reports of PSAI on the sex-typical characteristics, preferred toys, and play activities of children, and black and white photocopies of the left and right hand palms via mail. PSAI consisted of 12 masculine items and 12 feminine items, and a composite score was created by subtracting the feminine score from the masculine score, with higher scores representing masculine-typical behavior. While composite scores in PSAI were significantly higher in boys than in girls, 2D/4D was significantly lower in boys than in girls. Although the presence or absence of brothers or sisters affected the composite, masculine, and feminine scored of PSAI, a multivariate regression model revealed that 2D/4D negatively correlated with the composite scores of PSAI in boys, whereas no correlation was found in girls. Although 2D/4D negatively correlated with the masculine score in boys and girls, no correlation was observed between 2D/4D and the feminine score. In conclusion, although social factors, such as the existence of brother or sisters, affect dimorphic brain development and behavior in childhood, the present study revealed that the prenatal hormonal environment was an important factor influencing masculine-typical dimorphic brain development and behavior in school-aged children.
authors.affiliation: Department of Urology, University of Yamanashi Graduate School of Medical Science, Chuo-city, Japan.|Department of Urology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Mitsui
authors.affiliation: Hokkaido University Center for Environmental and Health Sciences, Sapporo, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Araki
authors.affiliation: Hokkaido University Center for Environmental and Health Sciences, Sapporo, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Miyashita
authors.affiliation: Hokkaido University Center for Environmental and Health Sciences, Sapporo, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Ito
authors.affiliation: Hokkaido University Center for Environmental and Health Sciences, Sapporo, Japan.
authors.forename: Tamiko
authors.initials: T
authors.lastname: Ikeno
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Seiko
authors.initials: S
authors.lastname: Sasaki
authors.affiliation: Department of Urology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Takeya
authors.initials: T
authors.lastname: Kitta
authors.affiliation: Department of Urology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Moriya
authors.affiliation: Department of Obstetrics and Gynecology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Cho
authors.affiliation: Department of Obstetrics and Gynecology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Morioka
authors.affiliation: Hokkaido University Center for Environmental and Health Sciences, Sapporo, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Kishi
authors.affiliation: Department of Urology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Shinohara
authors.affiliation: Department of Urology, University of Yamanashi Graduate School of Medical Science, Chuo-city, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takeda
authors.affiliation: Department of Urology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.|Department of Urology, Kushiro Rosai Hospital, Kushiro, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Nonomura
mesh_terms: D001519:Behavior; D005260:Female; D005385:Fingers / Q000033:anatomy & histology*; D006801:Humans; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D012574:Schools; D012727:Sex Characteristics; D035781:Siblings; D018709:Statistics, Nonparametric