A close look at your newborn baby boy's hand can tell you what he will look like when he grows up, say researchers.
A child's index finger to the ring finger ratio plays a role in the shape of a face – and it can be seen even before a boy hits puberty.
The research says that a close look at a newborn's hand can show much testosterone the child was subjected to while in the womb.
If the index finger is the same size or longer than the ring finger, the child is more likely to have a narrower chin and a more feminine face.
But if the index finger is shorter, the boy's face will be rounder and have a more masculine look.
Researcher Sonja Windhager, an anthropologist at the University of Vienna, told LiveScience: "The overall shape patterns associated with high and low digit ratios depicted in our sample of boys closely resemble the ones found for adult men.
"In an ongoing study, we are now collecting data of adolescents to compare the magnitude of shape difference associated with [second finger to fourth finger ratio] before and after puberty."