etymon vs parentage

etymon

noun
  • The original or earlier form of an inherited or borrowed word, affix, or morpheme either from an earlier period in a language's development, from an ancestral language, or from a foreign language. 

  • Meaning as derived and conveyed thereby: The literal meaning of a term according to its origin, which may differ from its usual meaning when the latter relies on idiomatic conventions that are not conveyed by the term alone (that is, they must be known in other ways, such as experience, training, education, or dictionary lookup). 

parentage

noun
  • Origin; derivation. 

  • The social quality of one's class in society. 

  • The identity and nature of one's parents, and in particular, the legitimacy of one's birth. 

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