When Charles Isaac Guy was born on 20 September 1864, in New South Wales, Australia, his father, Thomas Francis Guy, was 35 and his mother, Harriet Ballinger, was 35. He married Sophia Jane Cox on 20 June 1894, in Muswellbrook, New South Wales, Australia. They were the parents of at least 2 sons and 2 daughters. He died on 16 June 1943, in Maitland, New South Wales, Australia, at the age of 78, and was buried in Maitland, New South Wales, Australia.