Saving Grace: Backstory?

Late to the party as always, I’m catching up on DVD. I’m wondering about the details of the Hanadarko family as to birth order and childhood relationships.

Specifically, what’s the age and order placement difference between Grace and Father John? He’s not the oldest, but old enough to be in charge of her as kids*; yet he’s close enough to have made out with her friend Rhetta without being creepy.

Any source-based info, theories or WAGs welcome.

Oh, and Graham Chase is aging nicely.

*And thinks he still is.

All I remember off the top of my head is that her sister was younger. I think she’s older than the fireman and probably younger than all the rest, because they’re all used to picking on her, but that may just have been because she’s really, really tiny, and even a brother five or ten years younger would tower over her.

This is one of my favorite shows, and has some of the most amazing scenes I have ever seen.

IIRC, the sister was in the Murrah building doing an errand for Grace because Grace was hung over. I don’t have any idea how the “I see God” stuff started.