folk vs sibling

folk

noun
  • One’s relatives, especially one’s parents. 

  • People in general. 

  • The inhabitants of a region, especially the native inhabitants. 

  • A particular group of people. 

adj
  • Of or pertaining to common people as opposed to ruling classes or elites. 

  • Of or pertaining to the inhabitants of a land, their culture, tradition, or history. 

  • Of or related to local building materials and styles. 

  • Believed or transmitted by the common people; not academically correct or rigorous. 

sibling

noun
  • A person who shares a parent; one's brother or sister who one shares a parent with. 

  • A node in a data structure that shares its parent with another node. 

  • The most closely related species, or one of several most closely related species when none can be determined to be more closely related. 

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