I came across this phenomenon recently and shared it with my classes.

A new study in a British medical journal finds a link between the relative length of a woman's index and ring fingers and her athletic prowess.

The story I stumbled across claimed that the relative length of the ring finger was a function of the amount of testosterone washing through the system in the first pre-natal surge.

in 1998, British researcher John Thomas Manning suggested that the difference between male and female digit ratios stemmed from prenatal exposure to the hormones testosterone and estrogen. If the digit ratio -- which is established by the time a fetus is 9 weeks old and remains constant throughout a person's life -- reflects the level of that exposure, Manning reasoned, then it might serve as a marker for other conditions -- including predisposition to many diseases -- thought to be affected by prenatal hormone exposure.

But recent twin studies apparently suggest to some scientists that it's due mostly to the influence of genes.

Studying twins allowed his team "to look at the relative influences of genes and environment on finger ratios," Spector wrote via e-mail. "We found that 66 percent of the differences between people were due to genes -- i.e., heritable -- with no real influence of common or womb environment."

According to Spector, his study confirms that digit ratio is important in reflecting females' athletic prowess -- a finding already established among males. But, he wrote, "The twin study casts some doubt on the original testosterone in utero theory, as we would have expected to see an effect of the fetal environment influencing our twin studies. Our results suggest genes and not hormone levels are the predominant force in shaping sporting potential, and finger length is just a marker."

And then there is the question on what all this means. Maybe nothing.

Finger Forecasts - washingtonpost.com

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