I did not know this (from Wikipedia):

"When Milner was a teenager, he moved with his family to Los Angeles where his parents hired an acting coach and later an agent for the budding star. Milner had his first screen test and began his film career with his debut in the 1947 film Life with Father, in the role of John Day, the second oldest son of Clarence Day played by William Powell. Less than two weeks after filming for Life with Father ended in August 1946, Milner contracted poliomyelitis. He recovered within a year and had bit parts in two more films before graduating from North Hollywood High School in 1949."

He was very lucky to not have a pronounced limp or need braces or a wheelchair for the rest of his life.