Whoever his parents were, the first certain Count (Dutch graaf, Latin comes, French comte) of Loon was the 11th century Giselbert (modern Dutch Gijsbert, equivalent of modern English and French "Gilbert"). Exactly what territory he held is still uncertain, and his brother Arnulf is also mentioned as a count in various records. Although all of the charters which describe the brothers as siblings of bishop Balderic II of Liège are later forgeries, there is considered to be enough evidence to be accept this relationship.There are many mentions of the relationship, and medieval forgeries were often wholly or partly based on older real documents. : "Les documents qui éclairent les origines du prélat — documents diplomatiques faux ou suspects, sources narratives très tardives — sont loin d’offrir toutes les garanties. Nous estimons cependant que leur témoignage se fait l’écho d’une tradition basée sur la réalité." Vaes, following Baerten, emphasizes that in 1031, Bishop Reginard, Balderic II's successor, describes a grant made in the previous generation where Gislebert was named as both brother to Balderic and count of Loon. Kupper says that this document is also a false copy, though probably based on an older real act. "Cet acte est un faux qui se base probablement sur un document de 1026-1028"
