When Joseph Conway O'Leary was born on 10 November 1889, in Winchester, Frederick, Virginia, United States, his father, Daniel O'Leary Jr., was 36 and his mother, Mary Elizabeth Rose, was 24. He married Ethel Marie Haymaker on 24 December 1927, in Winchester, Virginia, United States. They were the parents of at least 1 son. He lived in Brunswick, Frederick, Maryland, United States in 1910. He died in March 1977, in Winchester, Virginia, United States, at the age of 87, and was buried in Winchester, Virginia, United States.