>We know that IQ is the most powerful predictor of success and that you can't train it into people by any known means

One very simple way of increasing IQ is to repeatedly take IQ tests. There is a noticeable uptick in recorded score for people who take the same type of test the second time within a twelve month period.

That suggests a method for finding the "true" IQ; keep taking the same kind of tests until your score plateaus.

In order to understand my position on "IQ", you should read the book "Hacking Darwin", which actually covers the question of what IQ is at length. I hope that it alters your position on IQ a little bit, what aspects of it are hereditary, and how the nature of life can alter it.