FILIATION. - It is the legal relationship between parents and children, or the relation of sonship. At the basis of the relationship of filiation there lies, in natural law, a bond of blood (consanguinity). But civil law also knows a form of relationship that is regulated as one of filiation, although the natural fact of generation is lacking (natural filiation and civil filiation). This latter relationship takes the name of adoption (v.), to which is attached the more attenuated relationship of affiliation (v.).
On the other hand, the fact of generation may take place within marriage or outside it. The law, while disapproving of the irregular relationship, regulates not only filiation secundum legem, but also all the various cases of children procreated outside marriage, while recognizing fullness of rights only to legitimate filiation, which constitutes the basis of the family in the proper sense. Moreover, illegitimate children, that is, those procreated outside marriage, are considered in different ways, according to the different condition in which they may come to find themselves. The term filiation is rather of civil-law usage, whereas in the CIC and in ethical doctrine the matter is comprised under other headings (family, children, legitimation, marriage, offspring, etc.).
For a single treatment of the whole complex of the juridical and ethical relationships of sonship, v. PROLE. Pietro Falarini