To be clear, I’m not saying studying this question is more important than anything else, just that research on it should not be suppressed, whatever the truth may be. This point was perhaps best put in the conclusion of this great paper on the topic:
The strategy – advocated by some influential scholars – of stigmatizing, suppressing, or downplaying evidence in favor of hereditarianism about group differences has been tried and has not worked. Research on this topic has been done and the results are widely available. Major psychology journals continue to publish work that deals openly with group differences (though researchers still debate about the relative contribution of genes and environment, and the question has not been settled definitively). Any measures that would be effective in preventing further work, such as those advocated by Kourany (2016), would have to be so severe that they would only attract even more attention to the findings they aimed to suppress. Science will carry on, and these questions will be answered. We should prepare in advance for the possibility that the genes underlying intelligence differences will not be distributed identically among ethnic groups. Failure to do this will only create a vacuum for “cranks rather than scientists” to opine on the nature and consequences of group differences (Anomaly, 2017, p. 293). Reich (2018) warns that if scientists “willfully abstain from laying out a rational framework for discussing human differences, [they] will leave a vacuum that will be filled by pseudoscience” (p. 258).
This paper has argued that the usual utilitarian reasons given for restricting intelligence research are not convincing and, in fact, there are strong reasons, both utilitarian and non-utilitarian, to favor free inquiry. For philosophers specifically, there is an additional consideration. For decades, the contribution of philosophers to this debate has consisted mostly in providing alternative explanations for evidence seeming to support hereditarianism about race differences (see Sesardic, 2000, 2005), and advocating various kinds of restriction and censorship (see Cofnas, 2016). This may be because hereditarianism is controversial, and philosophers are strongly disincentivized from pursuing lines of argument that lead to truly controversial conclusions. Testifying to how serious this problem is, Jeff McMahan, Francesca Minerva, and Peter Singer recently founded the Journal of Controversial Ideas, which will allow scholars to publish pseudonymously. Singer (2017) commented that “it’s unfortunate that such a journal should ever be considered necessary to enable controversial ideas to be published, but perhaps we have got to the point where it is.” It is not clear what kind of controversial ideas Singer had in mind, and the journal has not yet released its first issue, but it is hard to find a more controversial idea than hereditarianism about race differences in intelligence.
There is a danger for the philosophical community in putting our credibility on the line over the claim that race differences are entirely environmental. If work on genetics and neuroscience within the next decade produces convincing evidence that differences in measured intelligence among groups have a significant genetic component, there will be no way to conceal this information. The hereditarian explanation will have to be accepted, and people will know that philosophers were on the wrong side of the issue both scientifically and morally: scientifically, because we are supposed to be careful, disinterested commentators on scientific controversies, not activists supporting only the politically popular side; morally, because we did not help lay the groundwork for responding in a moral way to these facts that we should have known might be coming.
I don’t fault you for not reading it all, but it is a good resource for looking up specific topics. (I have summarized a few of the points here.) And I don’t think IQ is a flawed measure, since it is an important predictor for many measures of life success. Average national IQ is also fairly strongly correlated with measures of national welfare such as per Capita GDP.
To be clear, I’m not saying studying this question is more important than anything else, just that research on it should not be suppressed, whatever the truth may be. This point was perhaps best put in the conclusion of this great paper on the topic: