>kids all have the same potential in kindergarten and 1st grade. This statement is false. By this point, children have already been exposed to a large portion

>kids all have the same potential in kindergarten and 1st grade. This statement is false. By this point, children have already been exposed to a large portion of their parents' vocabulary even tangentially rather than directly. The amount of attention that kids receive can vary depending on their parents' schedules. The amount and quality of nutrition has a large impact on brain and cognitive development. That's not even accounting for base genetic differences, but these differences do impact the epigenetic control of expression of proteins.