It is unclear as to whether Celia's birth year was 1847 or 1846. Her grave stone says 1847, but her death record says March 12, 1846. It is believed that Celia's parents were Hugh and Mary Griffin Monahan, although her husband, the informant on her death record, stated they were Mall Monahan and Mary Stephen. Celia did have relatives by the name of Malachy (Mall) Monaghan and many Stephens first cousins, including a Mary Stephens. Family members of Malachy Monahan, son of Hugh and Mary Griffin Monahan, believe Celia was Malachy's sister. Malachy immigrated to the United States in 1861 and lived in New York, New Jersey and Chicago where he died. If it is true that Malachy and Celia were siblings as believed, Celia was from Knockroe, Mayo Abbey Parish, County Mayo, Ireland. Besides Malachy, she had another known brother, John, and a known sister, Eliza, who did not immigrate. John had a daughter named Celia and Eliza had a son named Malachy. Celia had a son named Hugh, which was her father's name. A descendant of Hugh Monaghan and Mary Griffin, Celia's parents, had an Ancestry.com DNA test and was shown to be a match with a descendant of Patrick Doherty, brother of Celia's husband. Therefore, the Monaghan's and Doherty's were apparently related.

Celia Monahan is on the 1870 census in Chicago, Illinois and listed as a servant. Another servant in the household is Kate Dority, age 22 and born in Ireland. It is believed that Kate Dority is the younger sister of Michael Doherty, Catherine, who was born May 20, 1849. Celia married Michael Doherty the following year in 1871 in St. Paul, MN. They moved to Wright County, Maple Lake, MN and had five children: Edward, John (Jack), Owen, Hugh and Anna.

Catherine (Kate) Doherty Raiche, sister of Celia's husband, Michael Doherty, is said in her obituary to have immigrated to the US with her mother in 1865. Her older siblings, Patrick and Michael Doherty, Mrs. Sam Raiche (Bridget) and Mrs. Ellen Fitzpatrick, had immigrated earlier. Kate's obituary says she lived for a time in NJ with her sister Ellen, NY, Louisville, KY, and Chicago where she was joined by her brother (Michael), her brother Patrick coming with Michael to MN and settling in Minneapolis where Celia and Michael were married, as well as Kate and her husband. After their marriage, they moved to Wright County, MN. This fits completely with Kate and Celia living as servants with a family in Chicago on the 1870 census, and Celia marrying Michael the following year in St. Paul/Minneapolis.