 Relatively little is known about Włostowic's youth, other than he was a scion of a relatively wealthy and powerful Silesian family, and became a trusted retainer of the duke of Poland, Bolesław III Wrymouth.Twentieth-century German medieval researchers saw Włostowic as a grandson of a Magnus, Count of Wrocław, who was described by the chronicler Gallus Anonymus as a royal who arrived in the 1070s from a land that had just fallen under the yoke of foreign rule.Some historians, most notably Tomasz Jurek, have postulated that Magnus, Count of Wrocław was in fact Magnus Haroldson, the son of the Anglo-Saxon king Harold II, who had fled England along with his siblings following the defeat of their father by William the Conqueror, thereby tracing Włostowic's ancestry to England.