After World War I, the St. Peter's church at Louvain had to be restored. When the floor of the choir was broken up, a vaulted tomb house, containing a heap of bones, was discovered. The study of the historical past of the church building was committed to Leo Van der Essen, Professor of History at the Louvain university, while Charles Nelis, Professor of Anatomy at the same university, was charged to identify, as far as possible, the discovered bones. Prof. Nelis succeeded in rebuilding three skeletons with bones that fitted together. He chiefly discovered on these skeletons a number of osteological variants, which in fact are known as being very rare; but their frequent existence on the three skeletons and their absence on the other bones, pointed towards an hereditary factor and the kinship of the three persons. By combining Prof. Van der Essen's historical data with his own heredomorphological findings, Prof. Nelis identified in the year 1930 the Dukes of Brabant from the twelfth and the thirteenth centuries, namely Godfrey II, Godfrey III and Henry I (father, son and grandson). With the help of the medical historian Dr. Tricot-Royer, Prof. Nelis extended his investigation to other members of the dukes' family, namely Saint Albert, Prince-bishop of Liège and brother of Henry I, whose shrine was preserved in Mechlin, and Henry II, son of Henry I, whose tomb was located in the ruins of the abbey of Villers-la-Ville. By measuring and digging in the gardens of the Affligem-abbey, according to historical documents, Dr. Tricot-Royer could find the graves and the skeletons of the first Duke Godfrey I with the Beard, of his daughter Queen Alice and of Godfrey of Gaesbeeck, brother of Henry II. Thanks to the unusual frequency of the same hereditary traits, the kinship with the first three skeletons was established and the historical indications could be confirmed by the anatomical science. The heredo-morphological pioneer research of Prof. Nelis on eight personages from five generations of the same family is unique.