Her year of birth can't be confirmed because there's no birth record and Anna Claflin's Bible hasn't been made public. Newspaper accounts and records suggest birth years between 1843 to 1846. Biographer Lois Beachy Underhill said she was born in 1843. The Lock Haven (NY) Express said that she was baptized in 1844 in Glen Union, Pennsylvania at the church at the mouth of Baker's Run but that seems unlikely since she said she was born in Homer, Licking, Ohio. The source for the claim by the Lock Haven Express was probably the folklorist Henry W. Shoemaker who told tall tales about the Claflin sisters. The Oct. 12, 1850 United States census records her age as 6 which would support the year 1843. The Claflin genealogy by Charles Henry Wight says she was born in 1845. The year 1845 is the most widely accepted date, with 1846 being another popularly accepted date.

Dates are difficult to pin down, but in adulthood she said she attended a Catholic convent school in Chicago when she was a child of about 13. In 1919 Bedelia Kehoe Garraghan reminisced about her Chicago classmate Tennessee Claflin from the year 1852. "How vividly I recall her as a child. She was very delicate and often went off in what her sister called a trance. Victoria would run for a cup of water, dash it on her sister's face and revive her." Tennessee's attendance at the school can't be confirmed because the school burned down in the Chicago fire.

Around 1856-1858 Tennessee began working as the "Wonderful Child," a clairvoyant physician. The earliest ad for the "Wonderful Child" that has been uncovered so far is from 1858, so that may be the year she began to work as a clairvoyant.

She married first John James Bortle on Sep 30, 1861 in Sycamore, Dekalb, Illinois and was said to have divorced him weeks later. Earlier that same year she was in Pittsburgh, Pennsylvania and saw Abraham Lincoln give a speech. Years later she claimed she knew that day that Lincoln would eventually be killed. "He will never leave the White House alive. I heard a pistol shot and saw the blood running from his head, and his coffin in the carriage with him."

In the 1870's she was one of the first female stockbrokers in New York as part of the firm Woodhull, Claflin & Company. She stylized her name then as Mrs. Tennie C. Claflin. The company was rumored to have been bankrolled by Cornelius Vanderbilt. She was also rumored to have been Vanderbilt's mistress. The extent of Vanderbilt's patronage isn't known for sure, but his stockbroker, Frank Work, who was the great-great-grandfather of Diana, Princess of Wales, used to frequent the home of Tennessee's sister Victoria Woodhull.

Tennessee ran for Congress in the 8th Congressional District of the state of New York while her sister and business partner Victoria Claflin Woodhull ran for President of the United States.

She married second Sir Francis Cook, 1st Baronet and Viscount of Monserrate in October 1885 in Kensington, Middlesex, England at St. Mary Abbot's Anglican Church.

In the 1890's the Dallas Morning News claimed Tennessee had married second George Collis in St. Louis and third John A. Green, who was a New York journalist. Marriage records have never been found to support the rumors. Tennessee denied ever marrying the men, but admitted to having a brief marriage with Bortle for which a marriage record does exist.

She liked to attend charity theater during WWI and at times had a box next to Princess Alexandra who treated her like a good friend. Lady Cook was known then for her wit.

She died at the home of her grand-niece and grand-nephew, Lady Utica Celestia Welles Beecham and Sir Thomas Beecham, the famous orchestra conductor. She died in the arms of Lady Beecham who took after her great-aunt in at least one respect. Utica claimed to have dreamed on May 5, 1910 that King Edward VII was dead. He died the following day.

She has no known descendants by either husband.