The length of a girl's ring finger could be an indicator of her future sporting potential, researchers at King's College London said on Thursday.
In the largest study of its kind, hand measurements of 607 female twins aged 25-79 from the UK were compared with the women's lifetime sporting achievements.
The findings, published in the British Journal of Sports Medicine, found that women with ring fingers longer than their index fingers had performed better at running and associated running sports such as soccer and tennis.
In women the ring finger is commonly shorter or the same length as the index finger, while in men the ring finger is generally longer.
The report said detection of sporting potential by examining the ratio between the index and ring fingers "could help identify talented individuals at a pre-competitive stage."
The reasons for the findings were unclear, said one of the report's authors, Professor Tim Spector from at King's College, who said he was originally sceptical about the link to sporting ability.
"Previous studies have suggested the change in finger length was due to changes in testosterone levels in the womb", he said.
But he said it had been found in a separate study of twins that finger length was largely inherited, possibly explaining why sporting parents often have sporting children.
"We found that finger length was 70 percent heritable with little influence of the womb environment," he said.
"This suggests that genes are the main factor and that finger length is a marker of your genes."
He said no specific candidate genes had been identified for the link and that multiple genes were probably responsible.
Previous studies looking at the link between finger length and sporting ability have mainly focused on men.
A study published in 2001 of 304 English professional soccer players found they had a significantly larger ring-to-index-finger ratio than a control group of 533 other men.