Playing a notable role in the early twelfth century fictional political saga Cogad Gáedel re Gallaib (CGG), Donovan is notorious for his alliance with his apparent father-in-law or at least relation Ivar of Limerick, the last Norse king of Limerick, and with Máel Muad mac Brain, king of Desmond, against the rising Dál gCais in the persons of Mathgamain mac Cennétig, king of Cashel, and his famous brother Brian Bóruma, later High King of Ireland. The latter would prove the victors, altering the political landscape of Munster and Ireland forever. It was Donovan's assistance that made Máel Muad King of Munster from 976 to 978.
The lineage of Donovan as set forth by John O'Donovan in the Appendix to the Annals of the Four Masters positions Donovan as the senior descendent of Oilioll Olum (d. 234 A.D.), and ultimately, the senior descent of the race of Heber. Such a lofty claim attracts considerable scrutiny, and Donovan's lineage suffers criticism as possibly missing a number of generations. It has been argued by one scholar, Donnchadh Ó Corráin, to possibly be a fabrication intended to link the Donovan dynasty to the Uí Chairpre Áebda, although Ó Corráin grudgingly allows that the pedigree may be syncopated. The genealogy of the ÚA CAIRPRI is set forth in Rawlinson B 502, an 11th-century manuscript, from Oilioll Olum to Cenn Faelad, who died approximately 744 A.D. It would appear that Donovan's grandfather, Uainide mac Cathail, is poorly documented, and undocumented in contemporary sources, appearing in the 12th century Caithréim Chellacháin Chaisil, and in records compiled in the 14th–16th centuries as being the grandson of Cenn Fáelad. Generally, five generations of descent will encompass more than 250 years. Other manuscripts have an additional two generations of descent during the 744 to 977 period. Ó Corráin's research does demonstrate that Donovan's ancestry was far from certain only a two hundred years after his death in 977. However, the author of the Caithréim had available to him an extensive collection of official Munster pedigrees and his inclusion of known historical figures for purposes of giving credibility to his propaganda tract would indicate the existence of the individuals.
Donnuban's accession to the kingship of Uí Fidgenti appears to be referred to in the mid 10th century Betha Adamnáin. But in this passage the acceding prince in Uí Fidgenti is actually said to belong to the Uí Echach Muman, another name for the Eóganacht Raithlind, an entirely separate dynasty from the southern region of Munster (Desmond), but curiously the one to which Máel Muad mac Brain, Donovan's close ally, happens to belong. With the recent collapse of the Eóganacht Chaisil the Uí Echach or Eóganacht Raithlind were the most powerful of all the Eóganachta remaining at this time. The prominent appearance of the Uí Fidgenti at the same time was undoubtedly related. In any case the passage in Betha Adamnáin is:
However, Herbert and Ó Riain believe this is an error, because the Uí Chairpre themselves also descend from a Laippe, and so they conclude Donovan belonged to a sept known as the Ceinél Laippe or Uí Laippe. Thus the passage can actually be used to support his descent from the Uí Chairpre. Notably both of his known sons are described as kings of Uí Chairpre. The Uí Echach may appear either for the above reason, namely Donovan's close association with Máel Muad, or because of influence from another part of the text, or because the name Laippe was found in their dynasty as well. None of this necessarily proves his descent from the early medieval Uí Chairpre but simply associates Donovan's family with the later kingship of their territories in the 10th century. There is no doubt however, regarding his classification as a member of the Ui Fidghente, as he is noted as Lord of the Ui Fidghente at the time of his death.
That Donovan's wife was the daughter of Imar of Limerick has long been the oral tradition of the family. Regardless of oral tradition, it has been argued that Donovan's mother was also Norse based on his father's other associations, by the 3rd Earl of Dunraven, who argued that his father Cathal's association through marriage with "Amlaf, king of the Danes of Munster" officially created the alliance between them. Something of this sort might even be hinted at in a 14th-century official pedigree, the earliest surviving, reprinted by Cú Choigcríche Ó Cléirigh in the early-mid 17th century, where his own father is given as Amlaíb (mac Cathail). The most commonly accepted genealogy is given by John O'Donovan.