His father asked him, when he was about 5 years old, what he wanted to be when he grew up. The little boy Walter Roberts replied, "I want to be an actor."
"Father chuckled at that," Roberts said. At least he prepared his parents early on for his future. Both his father and his mother in Nebraska were pianists and music teachers. His brother became a professional jazz trombonist and band leader. It was not out of the way for Roberts to turn to both music and the stage.
At the instance of his parents, he began learning to play the cello when he was 10, and for three years took part in the Nebraska Summer Music Festival. At school, he said, he was very much influenced by the acting coach.