How the length of our fingers points to our parents' income

Do wealthy mothers unknowingly give their sons the upper hand?

The ratio of a child's index and ring fingers goes hand in hand with their family's earnings, a major study suggests, owing to an unconscious evolutionary influence in utero.

2D:4D ratio
Credit: Professor John Manning, Swansea University.

Known as the Trivers–Willard hypothesis, it posits that women prenatally adjust their sex hormones to invest in either daughters or sons depending on maternal status,