PS. If genetic code dictates speed of growth and learning, why do we even need schools? Genetics should handle it all.
On the one hand the superiority of some students is denied. ( "All kids can catch up.") Then the supposed basis (in their mind) for its manifestation (genetics) is validated. ( "Its all genetics." ) The role of the child's innate desires is lost by reducing the argument to a social or material level.
This is a pretty complex bait and switch tactic. Each (false) argument is a ball of string for the mind's cat's eye. The yarn is to be chased without regard for whether than yarn should chased!!!
Nowhere is the right of the child to learn at their own pace discussed because the child does not matter. There are other goals that are more important.
