Incest. Illicit union between people who are related to the degree prohibited by the laws of God or of the Church.

Incest refers to the crime that is committed by this union, rather than to the union itself, which in certain times and in certain cases, has not been considered criminal: for, at the beginning of the world, and again for some time after the flood, marriages between brothers and sisters, between aunt and nephew, between first cousins, were permitted. The sons of Adam and Eve could not otherwise marry, no more than the sons and daughters of Noah, for a certain amount of time. In the times of Abraham and Isaac, these marriages were still allowed; and the Persians permitted them much later still, since it is said that these alliances are still practiced today among the remains of the ancient Persians. See Gabr.

Some authors think that marriages between brothers and sisters and other close relatives were permitted, or at least tolerated, until the time of the Law of Moses; that this legislator was the first who prohibited them to the Hebrews. Others hold the opposite view; and it is difficult to prove one or the other, due to lack of historical records of these ancient times.

The marriages prohibited by the Law of Moses are 1) between the son and his mother, or between the father and his daughter, and between the son and the step-mother. 2) Between brothers and sisters, whether they be brothers of the [same] father and mother, or only of one or the other. 3) Between the grandfather or the grandmother and their grandson or their granddaughter. 4) Between the daughter and the wife of the father and the son of the same father. 5) Between the aunt and the nephew; but the rabbis claim that the uncle was allowed to marry his niece. 6) Between the father-in-law and the mother-in-law. 7) Between the brother-in-law and the sister-in-law. However, there was an exception to this law, namely, that when a man died without children his brother was obliged to marry the widow in order to generate heirs for him. 8) It was prohibited for the same man to marry the wife and the daughter, or the daughter of the son of his own wife, or the daughter of her daughter, or the daughter of her daughter, or the sister of his wife, as Jacob did in marrying Rachel and Leah.

All these degrees of kinship in which it was not permitted to contract marriage are expressed in these four verses:

Moses prohibited all these incestuous marriages under penalty of having them annulled. Whoever , he says, will have committed any of these abominations shall perish in the midst of his people , that is, will be put to death. The majority of civilized peoples have regarded incest as an abominable crime; some have punished it with the highest form of torture. Only barbarians have allowed it. Calmet, Dictionnaire de la bible , vol. 2, pp. 368-369. [2]

Among Christians, not only kinship, but even alliance forms an annullable impediment to marriage, equivalent to kinship. A man cannot without dispensation from the Church contract a marriage after the death of his wife with any of the kin of his wife to the fourth degree, nor the wife after the death of her husband with those who are kin to her husband to the fourth degree. See Impediment.

The crime which a man commits with a nun, or a confessor with his female penitent, is called spiritual incest . The same term is used for the union of persons who have contracted some form of spiritual alliance or affinity. This affinity is contracted between a baptized person and the godfather and the godmother who have held him or her over the font, as well as between the godfather and the mother, the godmother and the father of the baptized child, between the person who baptizes and the baptized child, and the father and the mother of the baptized. This spiritual alliance renders null the marriage which would have been celebrated without dispensation and gives rise to a sort of spiritual incest , which is not however prohibited by civil laws, nor punishable like spiritual incest with a nun, or that of a confessor with his female penitent.

Notes

1. This ditty, based on verse 18 of Leviticus , comes from Calmet’s dictionary, cited below.

2. Antoine Calmet, Dictionnaire historique et critique de la Bible (Paris, 1722-28).