family tree vs sept

family tree

noun
  • The totality of someone's ancestors and offspring 

  • A diagrammatic representation of a pedigree, illustrating the connections between a person's ancestors, offspring and other relatives 

sept

noun
  • A clan, tribe, or family, proceeding from a common progenitor; especially, one of the ancient clans of Ireland. 

  • An enclosure; a railing. 

How often have the words family tree and sept occurred in a corpus of books? (source: Google Ngram Viewer )