"It is worth remembering that no genes related to difference in cognitive skills across the various racial and ethnic groups have ever been discovered.

Terrible argument. You don't need to have found the genes to know there are differences. Just because we don't know every gene associated with height yet and know whether they are more or less prevalent in different groups doesn't mean we can't know the average height in Japan is significantly lower than the average height in Denmark.

The argument for genetic differences has been carried forward largely by circumstantial evidence.

Well I'd say with all respect to Mr Hunt it's a lot better -- and not 'circumstantial' at all -- then there is for the idea that all humans in fact have the same potential for intelligence. That's actually an extraordinary claim and would be utterly miraculous in any standard theory of evolution that we didn't evolve profound cognitive differences given 40, 50, 60, 70 thousand years often of separate evolution. That is an extraordinary and miraculous claim and would basically require a rethinking of standard Darwinian theory and amazing proof and egalitarians have none. Just saying 'we haven't found the genes yet' doesn't mean an egalitarian has made his claim true.

Of course, tomorrow afternoon genetic mechanisms producing racial and ethnic differences in intelligence might be discovered,

Not to repeat myself but we can know there are differences without knowing specific genes. Those can come later.