Is it ensure, insure, or assure?
early 15c., from Old French paternal "of a father" (12c.), from Medieval Latin paternalis, from Latin paternus "of a father, fatherly," from pater (see father (n.)).
paternal pa·ter·nal (pə-tûr'nəl)adj.
Relating to or characteristic of a father or fatherhood.
Received or inherited from a father.
Related through one's father.