What is dr Seuss brother and sister names?

Theodor Seuss Geisel (Dr. Seuss) was born in 1904 and died in 1991.

His father's name was Theodor Robert Geisel. His mother was Henrietta Seuss Geisel.

He had an older sister Margaretha ("Marnie") and a younger sister, Henrietta, who died as an infant.

He was married twice (widower once).

He married his first wife, Helen Palmer, in 1926. She died in 1967.

Geisel married his second wife, Audrey Stone Dimond, in 1968.

Geisel had no children by either marriage.