[3][4] Eventually they lead through Ailill Érann to a descent from Óengus Tuirmech Temrach[5] and thus a distant kinship with the Connachta and Uí Néill, whose own pedigree is in fact unreliable before Túathal Techtmar.
[7] According to the Book of Glendalough (Rawlinson B 502) and Laud 610 pedigrees,[8][9] a brother of Dedu was Eochaid/Echdach mac Sin, from whom descend the Dál Fiatach of Ulster.
Eoin MacNeill finds the Conaille Muirtheimne to also descend from Dedu mac Sin, from another son Conall Anglonnach,[11] believing they are quite mistakenly thought to be Cruthin, as found in later genealogies.
[15] Through the House of Dunkeld and Conaire Mór, Dedu mac Sin is an ancestor of the modern British royal family.
The descent of the Dál Fiatach princes of Ulster from Dedu mac Sin is less secure, but nonetheless is supported by independent medieval sources (and contradicted by others).
As early as 1849, the great Irish scholar John O'Donovan noted that the pedigree of the Corcu Loígde, the leading historical descendants of the Dáirine, is corrupt for many of the generations preceding the legendary monarch Lugaid Mac Con.