In Gothic literature, the true genealogy of a character is often unknown or obscured at the beginning of the narrative, and is later revealed as a plot device. Bloodlines are important to Gothic explorations of inheritance, marriage rules, family, class, and sometimes ethnicity, so this tends to be a major plot point and is often closely related to the climax or denouement of the tale.

Examples of hidden and revealed genealogies are plentiful in Gothic novels. In Horace Walpole's Castle of Otranto, proper inheritance and marriage are both central to the revealed genealogy plot. Theodore is thought to be a peasant boy, and can therefore never marry Isabella or Matilda or inherit the castle. At a critical point in the narrative, however, Theodore is revealed to be the true prince, whose inheritance of Otranto was usurped by Manfred's grandfather. In fact, Theodore arguably has a stronger claim to the principality of Otranto than Manfred ever did, even though he hasn't lived there and was brought up in a different social class. Walpole's narrative choice to kill off the great-grandson of the usurper (Connor) on his wedding day seems to expand his critique beyond aristocratic primogeniture to also tie in to the practice of arranged marriage based on lineage.
Courtesy of Wendy Fall, Marquette University

Hughes, William, David Punter, and Andrew Smith. The Encyclopedia of the Gothic. Chichester, West Sussex, UK : Wiley-Blackwell, 2013. Print.