[1][2] She was the daughter of Henry IV, Holy Roman Emperor, and Bertha of Savoy.

They had two sons and three daughters: In 1977, German genealogist and historian Hansmartin Decker-Hauff revealed the existence of several other children he claimed to have found in documents from the abbey of Lorch, the Staufers' family monastery.

[7] Historian Heinz Bühler's suggestion that Berta of Boll, the wife of Count Adalbert of Elchingen-Ravenstein, was Agnes' and Frederick's daughter is purely speculative.

[8] Following Frederick's death in 1105,[9] Agnes married Leopold III (1073–1136), the Margrave of Austria (1095–1136).

In 2013, documentation regarding the results of DNA testing of the remains of the family buried in Klosterneuburg & Heiligenkreuz strongly favor that Adalbert was the son of Leopold and Agnes.