Your question has nothing to do with CRT, but with science (I am very critical to CRT if you want to know).
There is a scientific method to classify human beings by genetics. You can group by closeness of genetic code. When you do this you will arrive something similar to ethnicity NOT to race. Race classification is akin classification by eye color, while has some relationship to genetics - it has very little relationship and the genetic code similarities between two of ethnic groups, one has white skin, another have black skin, may be significantly larger than genetics similarity between two groups with black skin. This is why it is unscientific classification.