So, what is 'fair'? A new study claims that how we define fairness changes as we age.
Young children like all things to be equal, but older adolescents are more likely to consider merit when it comes to dividing up wealth, said the researchers.
As part of a research study in experimental economics in Norway, 500 school children had to work and then decide how to share their earnings.
The experiment studied both their willingness to share fairly and their perception of what is a fair distribution of income.
Researchers found that the shift from the "egalitarian" view of fairness to the more merit-based "meritocratic" view occurred largely between fifth and seventh grade.
However, it continued to change through high school, with seniors placing the most importance on achievement.
This transition likely results both from changes in the brain as it develops, and from exposure to new social experiences as we age, said the researchers.
For instance, children might participate in more and more activities in which a greater emphasis is placed on individual achievement as they grow up.
A better understanding of what people think is fair, and how this perception develops, might lead to changes in how institutions, such as schools, are set up, said study researcher Ingvild Almas, of the Norwegian School of Economics and Business Administration in Bergen, Norway.