John Manning and colleagues have used the ratio of the length of the index to the ring finger (2D:4D) as a proxy measure of in utero exposure to relatively more estrogen and less testosterone. In other words, a long index finger compared to the ring finger is an indicator of "feminization" in the womb, and a comparatively short index is a sign of "masculinization."
It turns out that there are large ethnic differences in the 2D:4D ratio. Manning is quoted as saying that, "There’s more difference between a Pole and a Finn than a man and a woman." According to the results of one study, "The Oriental Han had the highest mean 2D:4D, followed by the Caucasian Berbers and Uygurs, with the lowest mean ratios found in the Afro-Caribbean Jamaicans." In plainer language, Hans were the most feminized and Jamaicans the most masculine. You can read about a long list of characteristics associated with digit ratio here.
You gotta love citing studies that have Robert Trivers as a co-author.