Dorothea was born Dorothea Auguste Elizabeth on 11 February 1833 in Klein Vahlberg, Braunschweig, Germany to Henry George (Heinrich Georg) Grabenhorst and Anna Dorothea Elizabeth Neddemeier (aka Brandes). Dorothea was the only daughter of Henry George's children. She had a brother, Andrew, born in 1825, a brother Henry Christian born in 1829 and a brother, Frederick, born in 1835.

Dorothea's mother, also Dorothea, was Henry George's third wife. His first wife, Johanne Rosine Henriette Waupke, was the mother of Andrew and Henry Christian. She died 17 June 1831 from a rupture. Three months after Johanne Rosine Henriette’s death, Henry George married Anna Marie Juliane Maseberg. The marriage did not last. In an extraordinary move for that time in Germany, they were divorced. The reason for the divorce is unknown. It is known that a child, Johann Friedrich Andreas, was recorded in the church books as having been born to Anna Marie Juliane Maseberg and Heinrich Georg Grabenhorst five and a half months after their wedding on 9 Mar 1832 in Klein Vahlberg, Braunschweig, Germany. The little boy died one month later. One can speculate that perhaps this child was not the child of Henry George and thus the subsequent divorce. Whatever the reason for the divorce, this second marriage and the subsequent birth and death of the infant Johann Friedrich Andreas were not common knowledge to later generations of the family until the German researcher Walter Lehmann discovered it in the church record books. Henry George was always said to have been married twice, not three times as it turns out was the case.

Eight months after his marriage to Anna Marie Juliane Maseberg and two weeks after the death of the child, Johann Friedrich Andreas, Henry George married Dorothea's mother, Anna Dorothea Elizabeth Neddemeier, on 27 Apr 1832 in Wittmar, Braunschweig, Germany. In their marriage document he is listed as a divorced husband.  Anna Dorothea Elizabeth was the daughter of a carpenter named Brandes from Kissenbruck and the widow Catharina Elizabeth Lohr Neddemeier.  Illegitimate children born during this time in Germany were given the surname of their mother but their biological father was often listed on the birth record. Later, after moving to America, Dorothea maiden name was said to be Brandes or Branders.

At the time of her birth, Dorothea's father, Henry George, was working as a master tailor in Klein Vahlberg. Dorothea's family had always lived in this same area of Brunswick although they lived in several different villages. At the time of his wedding to Dorothea in 1832, Henry George, along with Andrew and Henry Christian, were living in Wittmar. In Wittmar Henry George worked as a tailor and baker.  In 1835 Dorothea's brother Frederick was born in Klein Vahlberg. In 1839 her brother Andrew was confirmed in Wittmar. In 1847 Dorothea was confirmed in Klein Winnigstedt. Frederick was also confirmed in Klein Winnigstedt in 1849. Like most Germans of that time, the Grabenhorsts belonged to the Lutheran Church. While living in Klein Winnigstedt, Henry George's occupations were recorded as a landlord and a baker and, shortly before the family immigrated to America in 1850, as the owner of a pub. 

In the spring of 1850, Dorothea, along with her father Henry George, her mother Dorothea, her brother Frederick and her brother Andrew left Klein Winnigstedt and traveled to Bremen where they boarded the ship Europe to go to America. They landed in New York on 27 May 1850 and joined Dorothea's brother, Henry Christian, in Chester County, Pennsylvania. Henry Christian had left Klein Winnigstedt for America in September of 1849 to check out whether or not immigration was feasible.  Obviously things were to his liking because he sent word for the rest of the family to come. Being industrious, the whole family wasted no time in getting jobs. In the 1850 census twenty four year old Andrew and twenty year old Henry Christian were listed as living in the household of Conrad Bode in East Vincent and working as laborers. Henry George and Dorothea were also living in East Vincent, Chester, Pennsylvania where he is working as a tailor. Seventeen year old Dorothea was living in the household of Joseph Ebner in East Vincent and working as a servant. Fifteen year old Frederick was also working as a laborer in East Vincent and is listed in the household of Samuel Whitby and also in the household of John Hause. It was here in Chester County that Dorothy met and married her first husband, Jacob Fischer, on 25 May 1853.

Dorothea's father, Henry George, did not want to pursue being a tailor in his new county. He started farming while in Pennsylvania but he was interested in owning his own farm. In the spring of 1854 he, his wife Dorothea, his son Frederick, daughter Dorothea and son-in-law Jacob moved to Illinois, locating eight miles north of Chicago. Dorothea and Jacob's first son, Henry Fisher, was born there on 10 July 1856.

Henry George and the rest of the family were not completely satisfied with what they found in Illinois and they made the decision to move to Iowa. In the summer of 1855 he went to Webster County, Iowa, and filed on two parcels of land totaling 315.40 acres or just under a half-section (320 acres) northeast of what would become Dayton. In the spring of 1856 Henry George, Dorothea, their son Frederick along with their daughter Dorothea,  son-in-law Jacob Fisher and Dorothea and Jacob's son Henry Fisher, moved into a log house that was standing on the 315 acres Henry George had filed on the summer before. In the 1856 Iowa State census Henry George, Dorothea, Frederick and Jacob and Dorothea Fisher are shown as residing and farming in Yell township, Webster, Iowa.  At that point, Dayton did not exist.  Their nearest post office was Homer, which was then the county seat of Webster County.  Iowa City was their nearest market where they had to go for supplies.  With the help of his son-in-law, Jacob Fisher, Henry George raised the first house in Dayton.

Dorothea and Jacob added five more children to their family while living and farming in the Dayton area. Caroline Dorothea was born in 1858, Jennie Johanna was born in 1860, Frederick Jacob was born in 1863, Ferdinand Maximillian (Max) was born in 1865 and Loretta was born in 1868. On 15 Oct 1868 Jacob died in Pilot Mound and was buried in the small private Schlicht family cemetery. He left Dorothea a widow with a large family to support. In the 1870 census she is living alone on her farm between Dayton and Pilot Mound with her children.

Two and a half years after Jacob's death, on 7 March 1871, Dorothea married Barnhardt Wolf, a widower with seven children, three daughters of whom were still loving at home. Barnhardt was born 1 April 1819 in Niederaula, Hesse-Kassel, Germany. He immigrated to America with his brothers in 1840 and moved to Illinois. In 1852 he was one of the first settlers to Yorktown township with his brothers: Jacob, John and Judah. Dorothea was Barnhardt's third wife. His first wife, Mary Ann Luther, died in 1864 at age 32. They were married in 1849 and had  six children: Louisa born in 1848, Caroline born in 1850, John born in 1851, William born in 1855, Elizabeth, born in 1859 and Mary Matilda (Tillie) born in 1862. In 1867 he married his second wife, Celia Balcom Heitz who also died. They had one daughter, Linda, born in 1867.  Dorothea and Barnhardt had three children together: Benjamin born in 1872, Lovina born in 1874, and Margaret (Maggie) born in 1877. Barnhardt died in 29 January1896 at age 76 in Yorktown.

In 1900 Dorothea's brother, Andrew, came to live with her after the death of his wife, Catherine. Prior to moving to Illinois, Andrew had lived in Chester county, Pennsylvania for many years.  On 26 Mar 1904 he died from a morphine overdose. According to the coroner's inquest he had been in the habit of taking small doses of morphine for years for various physical ailments and on the day of his death he had taken a larger dose because of a severe headache.

Dorothea died on 3 Nov 1914 in Loraine Twp, Henry, Illinois at age 81 and was buried in Hooppole Cemetery.