She had one full brother, Marshall Field Jr.[1] On January 1, 1891, Ethel married Arthur Magie Tree in an opulent ceremony held at the home of her parents, 1905 Prairie Avenue in Chicago.

Together, they were the parents of three children, only one of whom survived to adulthood: While married to Tree, she had an affair with British captain David Beatty.

Ten days after her divorce from Tree was made public, she was married to Captain Beatty on May 22, 1901, at the registry office, St. George's, Hanover Square in London with no family attending.

[7] Peter had birth complications that affected his eyesight and muscle control for the rest of his life, thought to originate from a venereal disease carried by Ethel.

Nicholas Duncan Beatty (who married writer Laura Keen, a granddaughter of Edward Curzon, 6th Earl Howe and sister of actor Will Keen and poet Alice Oswald), and Lady Miranda Katherine Beatty (wife of Alan Stewart, youngest son of Sir Dugald Stewart of Appin).