The only child of Orion and Mary "Mollie" Clemens, Jennie was born on 14 September,1855 in Keokuk, Iowa. Her uncle was Samuel Langhorne Clemens, better known as Mark Twain. Sam would come to know and love the little girl while he was staying with his brother and working at his printing office.

   Along with Jennies parents, Sam Clemens was at the child's bedside at the time of her death from meningitis.