The rates of developing capabilities differ between individuals for sure, but what you start with is far less important than what you end up with.
If we do not believe this, then the 'no child left behind' mentality will keep all education at the lowest level in each classroom. That is what is practiced today and is as wrong as it can possibly be wrong. Ask any USA public school teacher about this.
There's nothing wrong with that mentality. The problem is in the implementation.