He was Seigneur de Mortremer-sur-Eulane in Normandy. Cockayne's "Complete Peerage" (EU, p.152) says that he and ROBERT, COUNT OF EU commanded the Norman army at the battle of Mortremer in 1053/4. The DNB states that his mother was "the daughter of some unknown Danish chieftain and the sister of GUNNOR, the wife of DUKE RICHARD I of Normandy and of Herfast, the Dane, the grandfather of WILLIAM FITZOSBERN, EARL OF HEREFORD." This theory, however has not stood the test of time. The most current, though still unproven, theory is that Roger was the brother of RUDOLPHUS, SIRE DE WARENNE