Sibyl was called the "nepta" (either "niece" The historian
Frank Barlow also implies that she could have been Henry's daughter rather than his niece. Against this, Kathleen Thompson argues that Henry was not shy about recognizing his bastards, and that it is more likely that Sibyl was the illegitimate daughter of Henry's elder brother
Robert Curthose. Robert was
Duke of Normandy from 1086 (although he pawned it in 1096 to another brother,
William Rufus, to finance going on the
First Crusade), and
Falaise was where Robert's legitimate son,
William Clito, was being raised.
Katharine Keats-Rohan argues instead that Sibyl was the younger daughter of
William de Falaise and Geva de Burcy. Keats-Rohan says that Sibyl was just a "kinswoman" of Henry and not a bastard of either Henry or Robert. Thompson speculates that if Sibyl was the daughter of Robert, Sibyl's mother may have been someone employed in raising William Clito and that Sibyl was named for Robert's deceased wife,
Sibyl of Conversano. Baldwin had at least two sons – Stephen and Baldwin – and two daughters – Matilda Matilda was the mother of
Reginald fitzUrse, one of the murderers of
Thomas Becket. ==Notes==