Gaston III was the Viscount of Béarn in association with his father Centule IV

Centule IV of Béarn

Centule IV Gaston , called the Old, was the seventh Viscount of Béarn from 1012 to his death.He succeeded his father Gaston II while yet a minor, under a regency until 1022....

. His mother was Angela of Oloron. Despite the fact that he predeceased his father, Pierre de Marca

Pierre de Marca

Pierre de Marca was a French bishop and historian, born at Gan in Béarn of a family distinguished in the magistracy....

 proposed the hypothesis that he was associated with his father in the seventeenth century. Because he appears in the chroncles with an ordinal, this hypothesis is generally accepted by historians today.

Around 1030, he married the important Gascon lady Adalais (sister of the future duke of Gascony

Duke of Gascony

The Duchy of Vasconia , later known as Gascony, was a Merovingian creation: a frontier duchy on the Garonne, in the border with the rebel Basque tribes...

 and the viscount of Lomagne), with whom he had three children:

• Centule V
  Centule V of Béarn
  Centule V , called the Young, was the Viscount of Béarn from 1058 to his death. Centule increased the autonomy of the viscounts of Béarn and distanced them from the dukes of Aquitaine, to whom they owed theoretical vassalage...
  
  , who succeeded Centule IV
• Oliva
• Reina