Her father was born 69 years AFTER her? In any case, there is an Arnoul de Guines (1095) who married a Mahaut de St-Omer (1115), and it looks like this profile somehow accidentally matched up with that.
ARNOUL van Gent, son of WENEMAR [I] Burggraaf van Gent & his second wife Gisela de Guines (-Newton, England 1169, bur Saint-Inglevert).
m (before [1145]) MATHILDE de Saint-Omer, daughter of GUILLAUME [II] Châtelain de Saint-Omer & his wife Mélisende de Picquigny (-after [1145]).