Born Isabella Selmes, to Tilden and Martha Selmes, March 22, 1886 at Dinsmore in Boone County, Isabella's great-grandfather was James Dinsmore. Her father, Tilden Selmes, was a graduate of Yale University and in the 1880s headed west to settle in the Dakotas to establish a ranching enterprise. It was in the Dakotas that they became neighbors with Theodore Roosevelt. In 1895 Mr. Selmes passed away and a few years later her and her mother moved to New York, into the residence of Martha's sister Sarah, where Isabella entered Miss Chapin's School.