Women are paid less than men for the same work. We know this is a problem, and we know that the complex cultural factors behind it start young. Very young, according to Sheryl Sandberg, Facebook’s Chief Operating Officer and founder of the Lean In campaign.

Speaking in the session Progress Towards Parity at Davos, Sandberg said that “we have a toddler wage gap.” She went on to explain this startling claim:

“We assign our chores to our children in the United States, and it can be worse in other parts of the world… The boys are taking out the trash, it takes less time than cleaning the dishes and they get bigger allowances. We start out in our homes with these very different expectations and the time spent on these tasks is incredibly important.”

It doesn't stop there: "Mothers will systematically overestimate their sons' crawling, and underestimate their daughters'."

This may sound trivial, but such reflexive biases build up into barriers that have profound effects in the workplace.

"We attribute success differently," Sandberg said. We attribute a man’s success to his skills, while for women, we attribute it to working hard, help from others and getting lucky. "Men are promoted based on potential, women on what they’ve proven. Same as race. A white-sounding name on a resumé versus a black-sounding name is worth eight years of work on a resumé."