The children of that age have the ability to perceive the difference between the equal and unequal distribution of the food.
Scientists have also found that the children, who were altruistic and fair in the distribution of food, were also fairer in sharing their favorite toys.
In one experiment, children were shown movies of sharing foods. In which the children showed a sort of amazement when there is unfair distribution of eatables. In another experiment, when researchers asked children to give them their toys almost 2/3 children gave them the toys.
The researchers have reported,
“The current study provides the first evidence that by at least 15 months of age, human infants possess the rudiments of a sense of fairness in that they expect resources to be allocated equally when observing others (third-party fairness). Furthermore, our findings suggest that sharing non-essential resources (at high or low personal costs) with an unfamiliar adult is also prevalent at this age, which dovetails with natural observations of sharing behavior with familiar adults in young infants.”
Schmidt, M. F. H. et. al. (2011). Fairness Expectations and Altruistic Sharing in 15-Month-Old Human Infants. PLoS ONE 6(10): e23223