Genetic and Environmental Influences on 2D:4D Finger Length Ratios: A Study of Monozygotic and Dizygotic Male and Female Twins

  title={Genetic and Environmental Influences on 2D:4D Finger Length Ratios: A Study of Monozygotic and Dizygotic Male and Female Twins},
  author={Kyle L. Gobrogge and S. Marc Breedlove and Kelly L. Klump},
  journal={Archives of Sexual Behavior},
Recent studies have shown significant sex differences in the pattern of 2D:4D finger length ratios in humans and several other mammalian species. In humans, these ratios are suggested to be negatively correlated with prenatal exposure to testosterone, positively correlated with prenatal estrogen, and exhibit sex specific patterns of association with sexually dimorphic clinical phenotypes. However, the relative contributions of genetic and environmental influences on digit ratios in men and… 
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The existence of non-shared environmental influences that affect both 2D:4D and sexual orientation are suggested, which are in the predicted direction according to the prenatal hormone transfer hypothesis.
Finger Length Ratios of Identical Twins with Discordant Sexual Orientations
Examination of patterns in identical twins with discordant sexual orientations found males had more masculinized 2D:4D ratios than females, and this sex difference did not vary by sexual orientation.
Brief communication: Familial resemblance in digit ratio (2D:4D).
Familial resemblance in the second-to-fourth digit ratio (2D:4D), a proxy for prenatal androgen action, was studied in 1,260 individuals from 235 Austrian families and heritability estimates based on parent-child and full-sib dyad similarity indicated substantial genetic contributions to trait expression.
Depression Is Associated With the Absence of Sex Differences in the 2D:4D Ratio of the Right Hand
It is concluded that major depression is associated with an absence of sex differences in the 2D:4D ratio and did not correlate with depression severity even when examined for group and sex separately.
Digit Ratio (2D:4D), Abo Blood Type, and the Rhesus Factor
  • M. Voracek
  • Psychology, Biology
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  • 2008
Differences in 2D:4D by self-reported ABO blood type and Rhesus factor, two easily collectible genetic traits, in two samples were investigated and two consistent patterns emerged across samples, which may suggest genes contributing to the expression of 2D-4D reside in the vicinity of the gene loci of these blood groups or pleiotropic effects of the blood-group genes.
2D:4D Digit Ratios in Adults with Gender Dysphoria: A Comparison to Their Unaffected Same-Sex Heterosexual Siblings, Cisgender Heterosexual Men, and Cisgender Heterosexual Women.
We compared gender dysphoria (GD) patients and their same-sex siblings in terms of their 2D:4D ratios, which may reflect prenatal exposure to androgen, one of the possible etiological mechanisms
The Sex-Related Differences of Relationships between 2D : 4D Ratio and Electroencephalographic Coherence in Patients with Schizophrenia Compared with Controls
Low prenatal testosterone may play certain roles in altered correlation between 2D : 4D and cerebral laterality in schizophrenia and the development of schizophrenia by epigenetic mechanism.


Finger-Length Ratios in Female Monozygotic Twins Discordant for Sexual Orientation
Differences in 2D:4D ratio suggest that MZ twins share virtually the same genes, and lower ratio in lesbians is a result of differences in prenatal environment.
Heritability of the Second to Fourth Digit Ratio (2d:4d): A Twin Study
A substantial genetic contribution is suggested to the determination of this hormonally related skeletal ratio in women, which could be more influential than the effects of common prenatal environmental factors.
The 2nd:4th digit ratio, sexual dimorphism, population differences, and reproductive success. evidence for sexually antagonistic genes?
  • ManningBarley Szwed
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    Evolution and human behavior : official journal of the Human Behavior and Evolution Society
  • 2000
In-utero androgen exposure and 2nd to 4th digit length ratio-comparisons between healthy controls and females with classical congenital adrenal hyperplasia.
2D:4D ratios determined directly from radiographs of the left hand confirm significant differences between males and females, however, female patients with virilizing CAH do not have a male digit ratio pattern suggesting that in theleft hand digit ratio development is not influenced by in-utero exposure to androgens.
Fluctuating asymmetry, second to fourth finger length ratios and human sexual orientation
  • Q. Rahman
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  • 2005
Masculinized Finger Length Patterns in Human Males and Females with Congenital Adrenal Hyperplasia
Results are consistent with the idea that prenatal androgen exposure reduces the 2D:4D and plays a role in the establishment of the sex difference in human finger length patterns, and finger lengths may offer a retrospective marker of perinatal androgens exposure in humans.
The 2nd:4th digit ratio and asymmetry of hand performance in Jamaican children
Testosterone, particularly prenatal testosterone, has been implicated in the aetiology of many extragenital sexually dimorphic traits and it is suggested that the 2D:4D ratio may be associated with the expression of other sexuallyDimorphic behavioural traits.