Sibling-in-law
A relative by marriage through a sibling or spouse.
Last updated
A sibling-in-law is a person related by marriage through the spouse of one's sibling, the sibling of one's spouse, or the spouse of one's spouse's sibling. In Indian English, the spouse of one's sibling-in-law is specifically called a co-sibling (co-sister or co-brother). Siblings-in-law are connected by a type of kinship called affinity, meaning they are not related by blood.
Quick Facts
- Type
- Kinship relation
- Category
- Affinity
- Alternative names
- Brother-in-law
- sister-in-law
- co-sibling
- co-brother
- co-sister
- Cultural note
- In Judaism, yibbum allowed a man to wed his deceased brother's childless widow
Facts from the source article.
Lore & Background
Siblings-in-law are related by affinity, not by blood. The children of one's siblings-in-law are called nieces and nephews, optionally specified as 'by marriage' to distinguish from blood or adoptive relations. When one pair of siblings marries another pair of siblings, the siblings-in-law are doubly related—each through both a spouse and a sibling—and their children are double cousins.
Reader's Guide
The sibling-in-law relationship occupies a unique position between spousal and sibling bonds. One study found that relational closeness and satisfaction for all relationships in the triad of sibling, sibling-in-law, and spouse were correlated, and that the sibling-in-law relationship shared similarities with both spousal and sibling relationships.
In religious legal systems such as Islamic law (Sharia) and Jewish law (halakha), sexual relations between siblings-in-law are considered incestuous unless the spouse is no longer married. In Judaism, the custom of yibbum provided a non-obligatory duty for a man to marry his deceased brother's childless widow to produce progeny. These rules and customs highlight the cultural and legal significance of the sibling-in-law bond, which balances familial closeness with social and religious boundaries.
Frequently Asked Questions
What is a sibling-in-law?
A sibling-in-law is a family member you gain through marriage rather than blood, specifically the spouse of your sibling, your spouse's sibling, or the spouse of your spouse's sibling. It is a broad umbrella term that covers what most people casually call a brother-in-law or sister-in-law.
Do any religious or legal traditions restrict relationships between siblings-in-law?
Both Islamic law (Sharia) and Jewish law (halakha) forbid sexual relations between siblings-in-law as long as the marriage that created the bond is still in effect. Jewish tradition historically included an exception called yibbum, which allowed a man to wed his deceased brother's childless widow.
More in Family & Relationships
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Sibling-in-law (CC BY-SA 4.0).
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced