What relation is my great-niece to my nephew? Paternal is used to refer to anything pertaining to one's father. Maternal refers to the mother, so while a person's paternal grandparents are on the father's side, the maternal grandparents are those found on the mother's side of the family. People also use the terms paternal and maternal to refer to other members of a family tree, such as a maternal aunt or paternal cousins.