[greatwave1]

What evidence do you have that the biological limitations for mathematical ability meets people early in the spectrum?

I can think of several anecdotal counter-examples... students who seemed to have been falling behind, but with the right teacher were able to make significant improvements and become a top performer.

You can also take a look at many of the studies done on the educational gap, to see that better schooling can have a massive impact on secondary and post-secondary educational outcomes. Surely this wouldn't be the case if poor performers had some "biological limit" that prevented them from succeeding in high school math.