How well does second-to-fourth-digit ratio in hands correlate with other indications of masculinity in males?

Low second–to–fourth–digit (2D : 4D) ratios in hands have previously been used as a proxy for prenatal testosterone levels. Moreover, it has recently been suggested that prenatal testosterone levels may direct future masculinization. If true, 2D : 4D ratios should negatively correlate with traits in males that are developed and maintained by testosterone at puberty such as facial and body masculinity and testes volume. We failed to find significant correlations between 2D : 4D ratios and these traits.