In Teen Titans #19 it suggested that Cassie is the daughter of Wonder Woman’s brother Lennox. That would make Wonder Woman her aunt and Zeus now her grandfather instead of father.



More information in the interview here,
http://dcwomenkickingass.tumblr.com/post/55507813446/azzarello-confirms-connection-between-wonder-girl-and

I also learnt elsewhere that apparently the thing from the end of the first DCnU storyarc, where Diana removes her bracelets and gets even more powerful, was actually something that had already been established...