Open Question: How should we respond when asked to self-identify about ethnicity and race?

My letter to CUNY's Vice Chancellor for Human Resources Management

Dear VCHRM:

I have looked at the form you have asked we complete and I would appreciate your advice before proceeding. 

I don't identify with any of the nationalities provided (Nigerian, English, Ukrainian, etc.). I also do not identify with any of the continents offered as choices (African, Asian, European). The continents of North America, Central America, and Australia are not offered as choices. As far as I know, none of the ethnicities listed in your survey have contributed to my ancestry. According to family lore, my ethnic background includes Daco-Thracian, Gael, and Gallo-Swiss, but only a DNA test would provide scientific evidence (which I don't have). My skin color is light brownish with some red pigment. The only thing I can say for sure is that I am human being and a citizen of the United States. 

Throughout history identification by ethnicity, skin color, and nationality have been used to violent ends. The genocidal violence by militia groups in Darfur was ignited by claims of ethnic difference, when in fact in precolonial "Arab" and "African" communities of this region cohabited and share common ancestry. So perhaps you can understand why I am apprehensive about self-identifying in any other way than human. Can you please advise?