Depending on the trait you actually care about. If you care about bone geometry, you select some length of a bone, you want to measure. If you care about susceptibility for a certain sickness, you measure that.

It's not racist, because it doesn't say anything about the worth of the human or their rights. In fact, if you refuse to categorize and measure, because you consider this in itself to be evil, you can't actually cater to this specific person.