The Relationship between the Second-to-Fourth Digit Ratio and Behavioral Sexual Dimorphism in School-Aged Children

Mitsui, Takahiko; Araki, Atsuko; Miyashita, Chihiro; Ito, Sachiko; Ikeno, Taketo; Sasaki, Seiko; Kitta, Takeya; Moriya, Kyoji; Cho, Kazutoshi; Morioka, Keita; Kishi, Reiko; Shinohara, Nobuo; Takeda, Masayuki; Nonomura, Katsuya

doi:10.1371/journal.pone.0146849

Cited by 23 publications

(33 citation statements)

References 32 publications

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“…This finding is consistent with other studies that demonstrated a 2D:4D effect in males but not in females for attention deficit hyperactivity disorder symptoms (Martel et al 2008), fear reactivity (Bergman et al 2010), and sex-typical behavior (Mitsui et al 2016). In accordance with Martel et al (2008), we speculate that sex differences in intrauterine brain development (e.g., biochemical or anatomical aspects) might render males more vulnerable to the effects of prenatal androgenization than females.…”

Section: Discussionsupporting

confidence: 92%

Low digit ratio (2D:4D) in male suicide victims

et al. 2016

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Although women attempt suicides equally or more often than men do, men are more likely to die of suicide than women (sex paradox of suicidal behavior). Furthermore, the male traits of aggression and impulsivity predict suicide completion. Here, we studied the second-to-fourth-finger length ratio (2D:4D), a proxy for prenatal androgen exposure, in 46 suicide corpses and 25 non-suicide corpses. We report significantly lower 2D:4D in male suicide corpses than non-suicide corpses (p = .030, partial η 2 = .147). There was no significant association between 2D:4D and the suicide method. Our findings indicate increased risk of suicide following higher prenatal androgen exposure in males. The results may improve future efforts to predict and prevent suicides.

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Section: Discussionsupporting

confidence: 92%

Low digit ratio (2D:4D) in male suicide victims

et al. 2016

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“…Observations from CAH-affected females offer particularly strong evidence that gendered play behavior is affected by prenatal T (Berenbaum & Beltz, 2016;Hines et al, 2015). A number of studies had parents describe their child's play behavior with the Pre-School Activities Inventory (Golombok & Rust, 1993), which asks for the popularity of various play activities, in order to investigate the relationships with 2D:4D (Hönekopp & Thierfelder, 2009;Körner, Pause, & Heil, 2017;Mitsui et al, 2016;Wong & Hines, 2016). Analyses were performed separately for girls and boys.…”

Section: Convergent Results From Cah and Digit Ratio Beyond Gender Dymentioning

confidence: 99%

2D:4D Suggests a Role of Prenatal Testosterone in Gender Dysphoria

et al. 2020

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Gender dysphoria (GD) reflects distress caused by incongruence between one's experienced gender identity and one's natal (assigned) gender. Previous studies suggest that high levels of prenatal testosterone (T) in natal females and low levels in natal males might contribute to GD. Here, we investigated if the 2D:4D digit ratio, a biomarker of prenatal T effects, is related to GD. We first report results from a large Iranian sample, comparing 2D:4D in 104 transwomen and 89 transmen against controls of the same natal sex. We found significantly lower (less masculine) 2D:4D in transwomen compared to control men. We then conducted random-effects meta-analyses of relevant studies including our own (k = 6, N = 925 for transwomen and k = 6, N = 757 for transmen). In line with the hypothesized prenatal T effects, transwomen showed significantly feminized 2D:4D (d ≈ 0.24). Conversely, transmen showed masculinized 2D:4D (d ≈ − 0.28); however, large unaccounted heterogeneity across studies emerged, which makes this effect less meaningful. These findings support the idea that high levels of prenatal T in natal females and low levels in natal males play a part in the etiology of GD. As we discuss, this adds to the evidence demonstrating the convergent validity of 2D:4D as a marker of prenatal T effects.

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“…Supporting the validity of 2D:4D, three studies (Hönekopp & Thierfelder, 2009;Mitsui et al, 2016;Wong & Hines, 2016) have shown that children with lower 2D:4D (and, thus, supposedly higher testosterone exposure in utero) display more masculine play behavior (as described by the parents' answers on the Preschool Activities Inventory; PSAI; Golombok & Rust, 1993). Nevertheless, there is considerable discrepancy concerning the side of the hand (right/left) and the sex of the children in which the correlations were found (Hönekopp & Thierfelder, 2009: left 2D:4D of boys;Mitsui et al, 2016: right and left 2D:4D of boys; Wong & Hines, 2016: right 2D:4D of boys and right and left 2D:4D of girls).…”

Section: Introductionmentioning

confidence: 91%

“…Thus, amniocentesis studies, which are very rare due to the high effort involved, show inconsistent results. However, studies on the relationship between sex-typed play behavior and the ratio between the second and fourth digit length (a presumed marker for the prenatal testosterone level) show more consistent results (Hönekopp & Thierfelder, 2009;Mitsui et al, 2016;Wong & Hines, 2016). Following the observation that females have larger ratios between the second and fourth digit (2D:4D) than males, Manning, Scutt, Wilson, and Lewis-Jones (1998) suggested the 2D:4D as an easily accessible marker for prenatal testosterone exposure.…”

Section: Introductionmentioning

confidence: 99%

Parent-Reports of Sex-Typed Play Preference in Preschool Children: Relationships to 2D:4D Digit Ratio and Older Siblings’ Sex

et al. 2020

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Sex-typed play behavior shows large sex differences and seems to be affected by prenatal sex hormones. For example, a smaller, more male-typical ratio between the second and fourth digit length (2D:4D), a proposed marker for prenatal testosterone exposure, has been shown to be related to sex-typed play preference in childhood. Nevertheless, it is still being debated whether 2D:4D displays a stable sex difference throughout childhood, as there are few longitudinal studies. In the present study, children’s 2D:4D was measured on both hands on four occasions from early infancy to early childhood (T1: 5 months, T2: 9 months, T3: 20 months, and T4: 40 months) providing the rare possibility to test the temporal stability of the sex difference. Parents completed the Preschool Activities Inventory at T4 and reported on the number of older brothers and sisters as a measure for socialization influences. Parents described boys as playing more masculine and less feminine than girls. Boys had smaller 2D:4D than girls at all measurements (T1–T4) and on both hands (right/left). Nevertheless, 2D:4D increased significantly from T3 to T4 in both sexes. Girls, but not boys, who were described as playing more masculine and less feminine had more masculine 2D:4D ratios at T1–T4 on both hands (except for right 2D:4D at T2 and T3) and had more older brothers and fewer older sisters. These data underline the stability of the sex difference in 2D:4D and show the importance of both biological and social influences on sex-typed play behavior.

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The Relationship between the Second-to-Fourth Digit Ratio and Behavioral Sexual Dimorphism in School-Aged Children

Cited by 23 publications

References 32 publications

Low digit ratio (2D:4D) in male suicide victims

Low digit ratio (2D:4D) in male suicide victims

2D:4D Suggests a Role of Prenatal Testosterone in Gender Dysphoria

Parent-Reports of Sex-Typed Play Preference in Preschool Children: Relationships to 2D:4D Digit Ratio and Older Siblings’ Sex

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