This recent study examined 2D:4D digit ratios for 364 infants from birth through the second birthday. (Digit ratios are thought to reflect prenatal exposure and/or sensitivity to testosterone.) Six measures were taken: during the first month, the first and second birthdays, and both the left and right hands at each visit. I averaged the six measures for both boys and girls: Cohen's d for the difference between the boys'and girls' means is .167--a small difference.
The authors gave Cohen's d for the black-white differences for each of the six measures. I averaged them and got .383--a moderate difference with blacks being more masculinized. (The number might be an underestimate because they ignored the fathers and based racial classification on the mother's race alone. Mixed-race babies might have blurred the difference.) Anyway, in this study of prenatal testosterone, the size of the racial gap is more than double the gender gap.