Finger length

There are now many studies that show how the relative length of the ring and index fingers, known as the 2D:4D ratio, predict a variety of outcomes including susceptability to prostate cancer, sporting prowess, longevity and sexual orientation. It is believed that it reflects exposure to testosterone shortly after conception.
This newspaper article discusses how it predicts earnings amongst traders in the City. It would be interesting to see how it fares in a human capital model on a representative sample of the population. Since it is relatively easy to measure (as biomarkers go), hopefully it will be incorporated into datasets in the future.

Testorone and risk preferences

This might be of interest to risky-behaviour types:

Testosterone and financial risk preferences
Many human behaviors, from mating to food acquisition and aggressiveness, entail some degree of risk. Testosterone, a steroid hormone, has been implicated in a wide range of such behaviors in men. However, little is known about the specific relationship between testosterone and risk preferences. In this article, we explore the relationship between prenatal and pubertal testosterone exposure, current testosterone, and financial risk preferences in men. Using a sample of 98 men, we find that risk-taking in an investment game with potential for real monetary payoffs correlates positively with salivary testosterone levels and facial masculinity, with the latter being a proxy of pubertal hormone exposure. 2D:4D, which has been proposed as a proxy for prenatal hormone exposure, did not correlate significantly with risk preferences.
Apicella C.L. et al Evolution and Human Behavior 29 (2008) 384–390

Second-to-fourth digit ratio predicts success among high-frequency financial traders

"We found that 2D:4D predicted the traders’ long-term profitability as well as the number of years they remained in the business. 2D:4D also predicted the sensitivity of their profitability to increases both in circulating testosterone and in market volatility. Our results suggest that prenatal androgens increase risk preferences and promote more rapid visuomotor scanning and physical reflexes."

PNAS article - Coates et al. (2009)