Do we even know what turns someone into an Einstein? The sheer reason you even mention Einstein is because he was beyond exceptional. There have been millions of people to walk the face of this planet with astronomical IQs, but there has only been a handful of Einsteins, von Neumanns, Eulers, Mozarts, etc.. So few that the uttering of the names of these individuals carries strong meaning.

It's also worth noting that none of these individuals ever took an IQ test. Their genius is entirely recognized through their work. Which again raises the question of what exactly IQ testing and what IQ is adding to our understanding of exceptional ability.

It appears that over a century of research in psychometrics has demonstrated nothing we already could not infer. We do not need some boring puzzle test to tell us someone with Down syndrome will not be a Nobel Prize winner. Nor do we need some boring puzzle test to tell us that von Neumann or Mozart had godlike childhood abilities and could maybe make large contributions for humanity.