These debates remind me of the Sam Harris/Ezra Klein non-debate.
I have a few thoughts:
1. Your hypothesis seems very difficult to test. For starters the concept of race seems to be mostly a social construct. For example, the original homo-sapiens were black and it wasn't until a few thousand years ago (less than 10) that "white people" became dominant in Europe while other shades developed elsewhere. It gets even more complicated when you consider all of the variations of ancestry. And then there's the difficulty of controlling environmental factors.
2. If we set aside the fact that every human has "black" heritage. On the genetic side the thing you'd have to test is that the genes associated with dark skin are correlated to impulsivity. And ultimately you have to find a causal gene combination that links the two. Otherwise we're just talking about genealogy. "Those Milkoviches are a lawless group of scoundrels".
3. Identity science is probably no better than identity politics, likely worse. There are questions to explore, such as what Coleman Hughes has, like why American born blacks fare much worse than Island immigrant blacks (he has more examples). But the focus should be on the individual and not the perceived or {externally or self-identified} "race".
4. Social policy you elude to around race seems to me would be dangerous, crazy and counterproductive. So, what would be the point? If our genetic testing and such can help individuals know their risks, great, but on a "race" basis? Complete unhelpful.