Not sonship, because that excludes female children. Filiation is the relationship which exists between a child and the child’s parents, whether the parents are of the same or the opposite sex. The relationship can be established by blood, by law in certain cases, or by a judgment of adoption. Once filiation has been established, it creates rights and obligations for both the child and the parents, regardless of the circumstances of the child’s birth. originally from Latin "filius" - son.