There is a correlation between ring finger length and sexual preference.
the verdict
SUPPORTED
the evidence backs this
refutedsupported
the weight of evidence
2 sources for · 0 against
Recent peer-reviewed literature and a comprehensive meta-analysis report a correlation between index-to-ring finger length ratios (2D:4D) and human sexual orientation in both sexes.
The ratio of the lengths of the 2nd and 4th fingers (2D:4D) is a putative marker for prenatal gonadal hormone signaling and has been linked to human sexual orientation. Although 2D:4D is consistently found to be lower in males than females, the association with sexual orientation is variable across studies, with one meta-analysis finding lower (more masculine) digit ratios in lesbians than heterosexual females, but no overall association in males. However, this previous meta-analysis considered neither unpublished datasets nor bisexual individuals separately from homosexual and heterosexual individuals. Moreover, 17 datasets examining relationships between 2D:4D and sexual orientation have been published since that time, and we located an additional 11 unpublished datasets. We therefore conducted an updated and expanded meta-analysis comprising 51 studies, including 44 male and 34 female datasets, totaling 227,648 participants. This meta-analysis also explored whether 2D:4D differed between heterosexual and bisexual and/or non-exclusive individuals in both sexes. Results indicate lower (more male-typical) digit ratios in homosexual women (right hand g = 0.26, left hand g = 0.16; both adjusted following trim-and-fill), and higher (more female-typical) ratios in homosexual men (right hand g = −0.17, left hand g = −0.20; both adjusted) compared to heterosexual same-sex counterparts. Moderator analyses do not support publication bias for females. For males, positive findings were more likely to be published, but robustness tests, including trim-and-fill and leave-one-out, support the findings’ robustness. No significant differences were observed in 2D:4D between male or female bisexual and heterosexual individuals. These findings are consistent with evidence that prenatal androgens increase attraction to females and/or that prenatal estrogens increase attraction to males.
In laboratory animals, exposure to gonadal steroid hormones before and immediately after birth can exert permanent effects on many behaviors, particularly reproductive behaviors. The extent to which such effects occur in humans remains an open question, but several lines of evidence indicate that perinatal levels of both androgens and estrogens may affect adult human psychology and behavior, including sexual orientation and gender nonconformity. Some putative indicators of prenatal androgen exposure, including the ratio of the length of the index finger to that of the ring finger (2D:4D), have repeatedly indicated that lesbians, on average, were exposed to more prenatal androgens than straight women, suggesting that sufficient fetal androgen exposure predisposes a fetus to gynephilia (attraction to women) at maturity. The digit ratios of gay men do not differ from those of straight men, suggesting that prenatal androgen levels are not responsible for their androphilia (attraction to men). However, evidence that gay men who prefer an insertive anal sex role (ASR) have more masculine digit ratios than those preferring a receptive ASR suggests that early androgens influence some sexual preferences in men. Furthermore, digit ratios among gay men have been found to correlate with recalled childhood gender nonconformity (CGN). People with isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) offer further insight into the effects of perinatal gonadal steroid exposure. In people with IGD, gonadal hormone production is low or absent after the first trimester of gestation. However, because placental gonadotropins drive gonadal hormone secretion during the first trimester when genitalia sexually differentiate, individuals with IGD are unambiguously male or female at birth, consistent with their chromosomal and gonadal sex. Men with IGD report greater CGN, again suggesting that perinatal androgen exposure contributes to male-typical behavioral patterns in humans. Interestingly, women with IGD report less androphilia and more bisexuality than control women, suggesting that perinatal ovarian steroids in females typically augment androphilia in adulthood. Taken together, these findings indicate that the perinatal hormonal milieu influences human sexual orientation and gender conformity.
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