[Gormo]

How would you even define "race"? Does the concept as used in the common socio-cultural context have any consistent meaning with respect to physiology? If so, how would you measure it?

Being a member of a category isn't an inherent property of an individual thing; rather, including a specified set of individuals is what defines the category. If you try to study a phenomenon in general, but with preconceived notions about how each individual subject should be categorized, you're skewing your results straight from the outset.