fathership vs filiation

fathership

noun
  • The state of being a father; fatherhood; paternity. 

  • A title of respect addressed to a priest. 

filiation

noun
  • The determination of paternity. 

  • One that is derived from a parent or source; an offshoot. 

  • The condition of being a child of a specified parent. 

  • The ancestry or lineage shared by a group having the same bloodline. 

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