The Perlstein family is a recurring family in the franchise. Arnold, the first member introduced, is first seen in the book, At the Waterworks.
Arnold[]
Main article: Arnold Perlstein
Arnold is the son of Mr. and Mrs. Perlstein. He is also the paternal cousin of Janet. He was one of Professor Valerie Frizzle's former students, and is currently in Ms. Fiona Frizzle's class.
Mr. Perlstein[]
Mr. Perlstein is Arnold's father, Janet's uncle, and Mrs. Perlstein's husband. He is voiced by Elliott Gould in the episode, Going Batty.
He does not appear in the gene machine during Janet's Mystery Gene.
Mrs. Perlstein[]
Mrs. Perlstein is Arnold's mother, Janet's aunt, and Mr. Perlstein's wife. She appeared in many books of the classic series and Ms. Frizzle's Adventures series, as well as a few episodes of the original series, but she only spoke in the book, Lost in the Solar System.
Arnold and Janet's grandmother[]
Their grandmother was mentioned in the Holiday Special, when Arnold says that she is sick for the first night of Hanukkah, which is the reason they are not going to see The Nutcracker with Wanda and the others.
She was seen in the gene machine.
She is the husband of their grandfather.
Janet[]
Main article: Janet Perlstein
Janet is Arnold's bossy, know-it-all paternal cousin. She is the daughter of Mr. and Mrs. Perlstein.
Mr. Perlstein[]
Mr. Perlstein is Janet's father, Mrs. Perlstein's husband, Arnold's father's brother, and Arnold's paternal uncle.
Mrs. Perlstein[]
Mrs. Perlstein is Janet's mother, Mr. Perlstein's wife, and Arnold's paternal aunt.