offshoot vs sibling

offshoot

noun
  • That which develops from something else. 

  • That which shoots off or separates from a main stem or branch of a plant. 

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 offshoot and sibling occurred in a corpus of books? (source: Google Ngram Viewer )