If we know intelligence is largely genetic and differs across genetic phenotypes, it would tell us that public policies designed to alter group outcomes by altering the environment might be counterproductive.

To take an extreme example where genetics is the clear cause, cats are underrepresented in college. Because we know that cats are genetically less intelligent than humans, we can conclude that affirmative action/college for cats education programs/etc are a waste of money.

Another use would be knowing that if only 50% of the population has the intrinsic intelligence for college, college prep programs should not serve more than 50% of the population (modulo technical details).