Thanks for the reply!

For example, if it turns out that group A has a higher average IQ than group B, and that A and B can be distinguished reliably by genetic testing (including but not limited to visual inspection for associated phenotypes), I might decide to devote more effort to educating group B than group A, to make up for the difference. Or I might decide to devote more effort to educating group A than group B, to get the best bang for my education buck.

Fair enough, that's an example of policy, based on this data.

Or I might decide to research the differences, to learn more about the physiological mechanisms of intelligence.

Also cool, seems obvious in hindsight!

Or I might change my ways of evaluating claims so that I give more weight to group A's ideas relative to group B's than I used to (assuming I used to believe they were equally intelligent).

I'd imagine a group's ideas are more to do with non-genetic factors than genetic intelligence.

Or I might decide to structure my society in such a way that group A has access to certain privileges that group B is denied, on the grounds of their superiority, or such that B gets privileges A is denied, on the grounds of their greater need. Etc.

For me some of these would be contingent on the additional discovery that the group's intelligence is a result of its genetic difference; group B could be generally poorer, or less well-nourished, or some other factor leading to lower intelligence, in addition to being genetically distinguishable. This is also making the assumption that IQ tests are culturally fair and the like - though I'm happy to use the term as a placeholder for 'idealized intelligence test'.