 Sigtrygg was of Norse and Irish ancestry . He was a son of Olaf Cuarán ( also called Kváran ) , King of York and of Dublin , and Gormflaith ingen Murchada . Gormflaith was the daughter of the King of Leinster , Murchad mac Finn , and the sister of his successor , King Máel Mórda of Leinster . She had previously been married to the King of Meath and High King of Ireland , Máel Sechnaill — the first of her three husbands . She was a beautiful , powerful and intriguing Irish woman , who according to the 13th @-@ century Icelandic Njál 's saga , was " the fairest of all women , and best gifted in everything that was not in her own power , but it was the talk of men that she did all things ill over which she had any power " . Sigtrygg 's paternal half @-@ brother was Glúniairn , " Iron @-@ knee " , who ruled as King of Dublin from 980 – 989 . 
