Eddis, Attolia, Sounis

Ooh, this was sort of answered, I think, in RotT. Eugenides takes one look at his newborn daughter, the smile drains from his face, and he says that this one is Eugenia. He could tell, from birth, that she might become the next Thief and was basing her name on that. Maybe that same thing happened to his grandfather and he bullied his daughter and the MOW into naming our beloved Gen "Eugenides."

I'd guess that no one could be certain that this or that baby *would* become the thief; seems like Gen's mom sort of should have been but she died (fell) before she could.