Is step-sibling marriage incest?

[BornInMarch]

If a man marries his step-sister (the daughter of his father’s wife, but neither his father’s daughter nor his mother’s daughter), would that be considered incest? What about the reverse, where a man marries the mother of his daughter-in-law?

 

[1ke]

If a man marries his step-sister (the daughter of his father’s wife, but neither his father’s daughter nor his mother’s daughter), would that be considered incest?

Regarding the impediment, it depends upon whether a **legal adoption **occurred. If there is no legal adoption, there is no impediment to the step-sibling marriage (unless there is a civil law impediment in a particular place). If either were adopted by the parent of the other, this creates an impediment to marriage. It is an ecclesial law, and therefore can be dispensed.

Can. 1094 Those who are related in the direct line or in the** second degree of the collateral line** by a legal relationship arising from adoption cannot contract marriage together validly.

If
What about the reverse, where a man marries the mother of his daughter-in-law?

This isn’t the reverse. This is a different situation. Presumably the man in question is a widower who does not have a wife at the present time. His son is married and his daughter-in-law’s mother is similarly widowed and available. This is how your scenario reads to me.

If that is the case, no there isn’t currently an impediment to such a marriage.

The relationship created by marriage between a husband and his wife’s relatives and the wife and the husband’s relatives is called affinity, but in the current code affinity is limited to first degree in the direct line. There is no relationship of affinity between the husband’s relatives and the wife’s relatives under the current code of canon law.

Can. 1092 Affinity in the direct line in any degree invalidates a marriage.

Were his son to die, the father could not marry his daughter-in-law without a dispensation, as that would be affinity in the direct line.

 

[Sky_River]

Regarding the impediment, it depends upon whether a **legal adoption **occurred. If there is no legal adoption, there is no impediment to the step-sibling marriage (unless there is a civil law impediment in a particular place). If either were adopted by the parent of the other, this creates an impediment to marriage. It is an ecclesial law, and therefore can be dispensed.

Can. 1094 Those who are related in the direct line or in the** second degree of the collateral line** by a legal relationship arising from adoption cannot contract marriage together validly.

This isn’t the reverse. This is a different situation. Presumably the man in question is a widower who does not have a wife at the present time. His son is married and his daughter-in-law’s mother is similarly widowed and available. This is how your scenario reads to me.

If that is the case, no there isn’t currently an impediment to such a marriage.

The relationship created by marriage between a husband and his wife’s relatives and the wife and the husband’s relatives is called affinity, but in the current code affinity is limited to first degree in the direct line. There is no relationship of affinity between the husband’s relatives and the wife’s relatives under the current code of canon law.

Can. 1092 Affinity in the direct line in any degree invalidates a marriage.

Were his son to die, the father could not marry his daughter-in-law without a dispensation, as that would be affinity in the direct line.

What if its a celibate marriage?

 

[1ke]

What if its a celibate marriage?

What if what is a “celibate marriage”? I don’t understand the question or to which part you are referring. An impediment precludes any marriage at all, unless it is dispensed. Moreover, one can only enter marriage if one is willing to exercise conjugal rights if either party asks for it, even if a couple mutually agrees to remain continent for a time or indefinitely. Therefore your “celibate marriage” inquiry doesn’t really make any sense in this context.