It's sometimes very difficult to find answers to questions like this. Clara Barton, or at least the Clara Barton I have heard of was born December 25, 1821, she was a pioneer American teacher, nurse, and humanitarian. She is best remembered for organizing the American Red Cross.
She died at the age of 90 on April 12, 1912 in Glen Echo, Maryland. According to historical records Clara was never married and had no children. This is not to say she was a lesbian, in those days topics such as sex and especially sexuality were "hush-hush".
So I guess it would be more of speculation, unless other documents arise, such as private diaries, journal's etc, it may remain a mystery. Though back in those days it really wasn't too uncommon for a woman of her stature to remain unmarried and childless.
There have been several books written on the topic that may contain more information on her personal life. The Life of Clara Barton Founder of the American Red Cross is one (published 1969)
A list of all the books are: (note, the list does not guarantee that the books are still in print)
Barton, William E. The Life of Clara Barton Founder of the American Red Cross New York: AMS Press, (1969)
Hutchinson, John F. Champions of Charity: War and the Rise of the Red Cross Boulder: Westview Press, Inc., (1996)
Joyce, James Avery. Red Cross International and the Strategy of Peace New York: Oceana Publications, Inc., (1959)
Pryor, Elizabeth Brown. Clara Barton: Professional Angel Philadelphia: University of Pennsylvania Press, (1987)
Ross, Ishbel. Angel of the Battlefield: The Life of Clara Barton New York: Harper and Brothers Publishers, (1956)
Deady, Kathleen,W. "Clara Barton" Mankato:Capstone Press, (2003)
Numbering All the Bones by Ann Rinaldi features Clara Barton and Andersonville Prison, a Civil War prison with terrible conditions.
Safranski, Debby Burnett, "Angel of Andersonville, Prince of Tahiti: The Extraordinary Life of Dorence Atwater," Alling-Porterfield Publishing House, 2008
No, Clara Barton was a Universalist.
Clara Barton did have kids
Clara Barton was born on December 25, 1821.
Clarissa Harlowe Barton's nick name is Clara Barton.
Clara was born to her mother Sarah (Stone) Barton and her father Captain Stephen Barton.
Clara Barton's father was Stephen Barton and Clara Barton's mother was Sarah Stone Barton.
Clara Barton founded the American Red Cross.
No, Clara Barton was a Universalist.
Clara barton is real
You are wrong, Clara Barton did NOT explore
Clara barton and her largest obstacle
Clara Barton did have kids
Clara Barton <3krystal
Clara Barton was born on December 25, 1821.
Clarissa Harlowe Barton's nick name is Clara Barton.
Clara Barton's birth name is Clarissa Harlowe Barton.
Clara Barton's parents' names were Stephen and Sarah Barton.