Walter is the son of ---- G.H. (Grover Herman) Grau.
Grover was the youngest son of twin Detlef and Sophia Grau. Grover was born January 12, 1873, died in 1918 at the age of 45. He was married to Emma Kracht on April 17, 1895.
They had three sons; Walter, who served in the medical branch of the U. S. Army from 1916 to 1919 at Camp Cody in Deming, New Mexico, Amandus, who was a doctor in Denison, and Robert, who was a doctor in St. Paul.