FILIATION. - It is the juridical relationship between parents and children or the relationship of parentage. At the base of the relationship of filiation in natural law is a bond of blood (consanguinity). But civil law also recognizes a form of relationship that is regulated as filiation, even though the natural fact of generation is lacking (natural filiation and civil filiation). This latter relationship is called adoption (v.), to which is added the more attenuated relationship of affiliation (v.).
On the other hand, the fact of generation may occur within or outside of marriage. The law, while disapproving of irregular relationships, regulates not only filiation secundum legem, but also all the different cases of children procreated outside of marriage, while recognizing full rights only to legitimate filiation, which constitutes the basis of the family in the proper sense. Moreover, illegitimate children, i.e., those born outside of marriage, are treated differently according to the various conditions in which they may find themselves. The terminology is rather of civil law usage, whereas in the CIC and in the cited doctrine the subject is treated under other headings (family, children, legitimation, marriage, offspring, etc.).
For a unified treatment of the complex of juridical and ethical relationships of parentage, see PROLE. Pietro Palazzini.