Comment by andriesm

The real question is whether genetics is a substantial or a negligible influence on intelligence (or proxy measures like IQ).

If genetics is less than 5 percent I would consider that something worth ignoring.

If it is 10 percent it is substantial enough to make a difference at the extremes.

If it is 20 percent that is real serious business.

Anything higher means we should really sit up and take notice of this fact.