The key point is it’s not just ethically wrong, but it’s not scientific because it’s subjective and has no basis in reality. For instance, you cannot use genetic studies to define a race because for instance, in Africa, you could have massive genetic diversity in people that are 200 miles apart. That doesn’t make them different races. If you did attempt to classify people into races based on something scientific like genetics, you would end up with hundreds of thousands of “races”. With even more fine tooth classification, you could subdivide those people into further sub groups that becomes indistinguishable from just classifying extended families.