More controversially, researchers have also suggested a link between both male and female homosexuality and digit ratio, but other research has found no effect.Physical aggression, too, has been linked to longer ring fingers, especially in men.Exactly how testosterone affects the foetal digit ratio is not clear.One theory is that for a certain time in foetal development, there are testosterone receptors on the fingers, and that the ring finger may have more of these receptors and therefore more likely to grow faster when exposed to higher levels of the hormone.
Top athletes have longer ring fingers – and women with larger hips have more intelligent children.
In his latest study, Professor Manning found that young men with long ring fingers were faster at sprinting than boys with relatively long index fingers.
One theory is that higher testosterone exposure in the womb may also have an influence on the developing vascular and respiratory systems, improving the aerobic capacity of the body and to a lesser extent increasing strength.
"It may be that there are more receptors on the ring finger than the index finger.
It is interesting that if you look at the back of the fingers, people are more likely to have hairs on the middle part between the two joints of the ring finger than the index.
They seem to appear around week eight, but by week 14 they have gone.