It is probably correct but very difficult to solve for, it can take centuries, which is not what most people want to hear. Cultural shifts are faster than biological evolution but are not always as fast as many people suppose.
Personally I believe in the use of eugenics for both blacks and whites in order to create an improved type of human. We know high IQ has, among others, the side affect of sharply declining propensity for violent crime. We know people with good health are able to think longer term than the sickly.
This goes way beyond the usual discussions but I think it is on the table whether people like it or not. I realize that the majority of people think this issue was laid to rest mid-twentieth century, but it is obvious those questions were always going to come back and it is only a matter of time. We've already been doing moderated forms of eugenics for decades except we've given it a hundred other names.
I say that as an Irish person. We've made considerable progress since in the late 20th century to the present, and now we are better in most metrics than the British (and perhaps they have also fallen), but don't imagine we were all sweetness and light in the past. Present day Irish have undergone a terrific cultural shift, evidence of which would be a supposed Catholic majority country voting in gay marriage.
We're still Irish, but we're mostly better than we were. Now if we could only resuscitate the courage of our grandparents we'd be in better shape yet.