That's because collectively the writers are contradictory in what they want to do with the character.
She was introduced as seemingly a peer to Nightwing, and really he was the one who welcomed her to the Batfamily in the first place: all things considered she seemed to be of his generation IMO. Then in her (1st) solo she's a contemporary of Batman and 32, and independent from him (she refuses his offer to join the Batfam). Next time we see her she's suddenly his younger cousin (all implications they didn't know each other before), and accepts his offer to join the Batfam. Second solo she's de-aged to 27, doing globetrotting to hunt down The Many Arms of Death on Batman's orders, and Julia is her Pennyworth that's it's revealed Batman sent to spy on and babysit her.
That's all I can be bothered with for now, ugh.