When Henry John Aiken was born on 30 May 1864, in Crawfordsburn, County Down, Ireland, his father, Henry J. Aiken, was 29 and his mother, Jane Robinson, was 30. He married Harriett Banker Roundtree on 8 March 1899, in East Whittier, Los Angeles, California, United States. They were the parents of at least 2 sons and 5 daughters. He lived in Los Nietos, Los Angeles, California, United States in 1910. He died on 27 June 1945, in Whittier, Los Angeles, California, United States, at the age of 81, and was buried in Whittier, Los Angeles, California, United States.