It's widely assumed that since she was adopted by Sidonia and there is no mention of her parents that she's an orphan just like Suske. Although this is never really mentioned in the comic books. Unlike Suske, Sidonia is her real aunt and she also has an older brother called Rikki.
Wiske made her first appearance in 1946 in the comic book De Avonturen Van Rikki en Wiske published by Standaard Uitgeverij. She was created by writer and artist Willy Vandersteen who gained the title of spiritual father to Suske & Wiske.
Wiske is portrayed with a tremendous love for her doll Schanulleke whom she never leaves without. She will always do everything she can to help people and animal alike. She does however have a very bad temper and is quickly jealous, mostly when it involves Suske getting attention from another girl. Just like with Suske they tried to update her appearance from the white dress to more modern clothing. However, this did not go over well with the fans and it was quickly undone.