I've retracted the civilization thing because it's not clear what it even means.

Well, historically, it meant the idea that they couldn't produce or participate in civilizations, due to poor impulse control or whatever. But fair enough, that was always your least defensible claim.

I would expect only a very weak link here in my hometown (vancouver), a strong link in US and european cities)

As has already been pointed out, if you expect the link to be weaker in different societies, than the link is caused by society. If you compare people of different races raised and living in the same conditions, and there's no difference, then racism is wrong. If there is a difference - for example, if black men are still just as likely to commit crimes - then, and only then, do you have a point. Consider slave-owners who refused to educate slaves because they were stupid - of course they were, when did you last meet a slave who could read or write?