Your character's heir is whomever in their family you the player names as their heir. Their is no restriction on gender. If your family is extensive enough, the heir can be a grandchild or a more distant relation. After your character dies permanently, its heir will become a playing character (PC), and will inherit all the properties of the dead character that it is eligible for. Some titles and positions will not be inherited automatically, but will depend on the degree of success and renown the dead character has achieved in the for of Story Points. You as the player will still "own" the same family as the dead player, through the heir.