I just realized that she has black hair like the mc & Ziva as well as similar tan skin like the priestess so don't tell me... dum dum dum! Ziva's his maternal half-sister?
OR Now here me out here, the mythical Qetesh was just the Greek name for the Mesopotamian goddess Ishtar. Her having a more middle-eastern complexion would suite this origin.
I always assumed Ziva's apperance & name was a reference to the fact she comes from PQ's version of the middle east (she isnt from the Weirdwood area after all). I could be wrong but it would be a nice reference to the actual mythic origins of the figure even if PQ follows it's own mythos & lore.
Also that would me Tinkerer has to retroactively include Ziva into the patch, which would be hazardous for the majority of the Main Quests.