Whether or not ethnicity is a causal factor is irrelevant. Even if it is a causal factor, it is still an injustice to act on it.
And if you didn't care about justice and just wanted to achieve an optimal prediction, whether or not it's a causal factor doesn't actually matter. Probability theory does not require a causal link.
"If it is rainy then it is cloudy." Is a valid inference despite the fact that rain does not cause clouds.
It is not, at least locally (because sunshowers happen.)