Thank you for your replies. I guess <trait> may be good enough.
am currently working with prosopographic descriptions of XVII Century European writers, historians and scientists. There is no information recorded about race or ethnicity... I guess that is because they were all white and caucasian, but
maybe this is a wrong assumption (it would be great to find it out).
The question arose in the context of a theoretical discussion about representing identity with TEI. I do not have a user case, but I think encoding and retrieving race might be relevant in projects that focus on contemporary writers and artists.