Does 2D4D correlate to anal sex role on gay men?
Executive summary
A handful of studies report that among gay men those who prefer an insertive anal-sex role ("tops") show lower, more male-typical right-hand 2D:4D ratios than those who prefer receptive roles ("bottoms"), but the effect is small and not consistently replicated across broader samples [1] [2] [3]. Large-scale reviews and meta-analyses find mixed results for 2D:4D and male sexual orientation overall and caution that any reported within-group associations are tentative, heterogeneous, and likely to be small [4] [5] [6].
1. The studies that claim a role: a specific within-group finding
Targeted research has found an association between anal sex role (ASR) preference among gay men and digit ratio: the 2021 Scientific Reports paper and related reprints report that Tops had lower (male-typical) right-hand 2D:4D than Bottoms, and that right-hand 2D:4D correlated with recalled gender nonconformity in that sample [1] [2]. Earlier papers and re-analyses likewise highlighted similar patterns and proposed prenatal androgen exposure as a plausible developmental mechanism linking 2D:4D to sex-role preferences [3] [7].
2. The broader literature: inconsistent and often null for men
When the lens is widened beyond single small samples, the picture clouds: meta-analyses and larger studies report mixed outcomes for 2D:4D and male sexual orientation—some studies show higher, lower, or no differences between gay and heterosexual men—and an influential meta-analysis found no consistent association for men overall [4] [6]. A recent review and meta-analytic updates emphasize that reported relationships vary by hand measured, sample composition, and methodology, and that many effects are small with replication failures [5] [8].
3. Methodological and interpretive caveats that matter
Several methodological issues limit strong conclusions: digit-ratio measurement methods differ between studies, samples vary in size and ethnicity, and some reported associations disappear when non-exclusive same-sex attracted men are included or when analyses control for heterogeneity—issues explicitly noted by the 2021 study itself and subsequent meta-analytic work [2] [6]. Meta-analysts warn that small effect sizes, publication bias, and heterogeneity across populations make any single-study finding provisional at best [5] [4].
4. What the evidence does and does not show about causation
Even where an association is observed, the evidence is correlational and retrospective: 2D:4D is a putative proxy for prenatal androgen exposure, and tying that proxy to complex adult sexual behavior or role preference does not establish a causal developmental pathway [3] [8]. Authors who report ASR–2D:4D links generally frame them as suggestive of prenatal influences rather than definitive proof, and larger syntheses explicitly report that links between 2D:4D and male sexual orientation remain unclear [1] [6].
5. Social and scientific implications—why this debate matters
Claims that finger length predicts sexual roles risk over-simplifying human sexuality and feeding biological determinism narratives; the literature’s own mixed results and authors’ cautionary notes underscore that effect sizes are small and context-dependent, and that alternative explanations (measurement error, population stratification, psychosocial factors) remain plausible and are discussed in source studies and reviews [5] [4]. The responsible reading of the evidence is that a specific within-group correlation has been reported and merits further study, but it is not robust, generalizable, or mechanistically proven at this time [1] [6].