The 1664 Northants vis’n says his father was Sir John Cave of Yorks, but no further information.  However the none-too-reliable Yorks 1563-4 vis’n does have a very sketchy pedigree for this family.  It repeats that Piers’ father was John (but no ‘Sir’) who was of Cave, Yorks, and says that Pyers Cave was the 5th son and the farmer of the Manor of Stanford belonging to Selby Abbey.  An explanation of Piers’ role is to be seen that his elder brother, John, the 3rd son, was Abbot of Selby.

Robert O’Connor found that his wife was Mary, dau. of Thos Burdett of Rowell, Northants.  He also produced a long genealogy of ancestors which he said was not cast iron, consisting of a line of Caves starting with the mandatory companion of the Conqueror.