Early in Jumanji (1995) we learn Judy and Peter's parents died in an accident while they were young. Instead, the children were raised by a woman named Nora.
I don't remember the film explaining who Nora was, or why she presumably adopted Judy and Peter.
Is Nora’s relation with Judy and Peter ever explained?
She is Peter and Judy's aunt.
"Wait! The instructions say if we finish the game it'll all go away. We'd better do it, or Aunt Nora's going to pitch a fit."
--- Jumanji, 1995, circa 27:50
According to various online references (IMDB, Wikipedia, Google) her full name is Nora Shepherd, which would make her their father's sister.
Nora says:
That sounds lovely. I'm sure you and your kids are gonna be very happy here.
Oh. Well, actually, they're my late brother's. He and his wife passed away just last winter.
So, she is their aunt on their father's side.
