Katherine, known as Katie, was the second of five children of Felix Dondeville and Margaret Schmidt. She was born on August 23, 1861 and was baptized December 12, 1861 at Saints Peter and Paul Church. On January 30, 1883, Kathleen was married in St. Louis to Christian Offer, a German immigrant who had come originally to Clinton County, Illinois. Two daughters were born to that marriage, Armanda (Maddie) in June 1887, and Amelia in December 1888. At some time in the 1890s, Offer enlisted in the United States Navy. The 1900 census recorded Katie, and her two daughters, living at 3241 California Avenue with her father.

Christian H. Offer died of pneumonia on February 22, 1905, while serving with the United States Navy in Cavite, Philippines. His body was returned to St. Louis for burial on June 29,1905 at Calvary Cemetery in St. Louis. His death certificate listed his marital status as single. One could assume from this that Katie had predeceased him. There is no further information on Amanda or Amelia Offer at this writing.