He was the second son of Eustace II, Count of Boulogne, and Ida of Lorraine (daughter of Godfrey III, Duke of Lower Lorraine and his wife, Doda). As second son, he had fewer opportunities than his older brother and seemed destined to become just one more minor knight in service to a rich landed nobleman. However, his uncle on his mother's side, Godfrey the Hunchback, Duke of Lower Lorraine, died childless and named his nephew, Godfrey of Bouillon, as his heir and next in line to his duchy of Lower Lorraine. This duchy was an important one at the time, serving as a buffer between the kingdom of France and the German lands.