On the Science of Changing Sex

Gay Men’s Hands Tell Us About Their Erotic Role

Posted in Brain Sex by Kay Brown on March 17, 2023

Thirteen years ago, I wrote an essay on how scientists had been frustrated using the 2D:4D digit ratio to demonstrate that gays and transsexuals had anomalous pre-natal exposure to androgens. They had gotten very confusing, contradictory results. I’ve been following the research hoping that some headway would be made. Well, maybe we have.

First was the confusion of not segregating and analyzing transsexual subjects data based on etiology / sexual orientation. We may now have found a similar issue with looking at gay men. There is strong evidence that there is an etiological difference between subsets of androphilic males that has correlates with preferred erotic role, specifically, preferring receptive anal sex vs. everything else.

There have also had some scientists questioning whether the 2D:4D is really about androgen exposure at all. Some data suggests that the differences within, but not across the sexes, may be due to other factors such as stress induced cortisol exposure, etc. But for our purposes, that does not matter. What matters is that when we see data that differentiates between populations and correlates with other markers for those populations, we have something interesting to note and explore. Such is the case with the Swift-Gallant paper on 2D:4D difference between tops and bottoms.

“A growing body of work indicates that anal sex role (ASR) preferences may serve as a proxy for subgroups of gay men who differ in development and gender conformity. Thus, in the present study we asked whether gay men with different ASR preferences may differ in 2D:4D. We hypothesized that gay men with a Bottom ASR (receptive), who tend to be more gender nonconforming (GNC), would have a higher (more female-typical) average digit ratio than ASR Tops (insertive), who tend to be more gender conforming. We predicted that gay men with a Versatile ASR preference (i.e., preference for insertive and receptive) would be intermediate between these two groups in both GNC and 2D:4D.”

The data they gathered is remarkable. The statistical difference between the tops and bottoms was d=0.63 for their right hands. Compare this to the difference between control men and women (from another study) at d=0.76. Thus the difference is nearly as large as that between men and women. This is a dramatic result!

They found that versatiles, those that both top and bottom were intermediate between the two. There are two hypotheses that would explain this. One is that this is a dimensional trait that smoothly varies between tops and bottoms. The other is that this is in fact, taxonic, and those that self-labeled as “versatile” were in fact an admixture of the taxonomically distinct tops and bottoms. The data presented does not allow us to determine this.

I’m predicting that the later hypothesis is correct, based on the fact that earlier work supported that, especially since the obligate bottoms appear to be the only subset of androphilic males who exhibit the Fraternal Birth Order Effect.

Further Reading:

2010 Essay on 2D:4D frustrations

Essay on Etiological Differences between Tops & Bottoms

Essay on Socio-Economic Status effecting 2D:4D differences

Essay on 2D:4D study that supports transsexual taxonomy.


Swift-Gallant, A., Di Rita, V., Major, C.A. et al. Differences in digit ratios between gay men who prefer receptive versus insertive sex roles indicate a role for prenatal androgen. Sci Rep 11, 8102 (2021). https://doi.org/10.1038/s41598-021-87338-0

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