Man catches Sister-in-law with another man | Agni Varsha Part 4 | Hindi Movi

One’s sibling-in-law is one’s spouse’s sibling, or one’s sibling’s spouse. By gender, this is specified as brother-in-law for one’s spouse’s brother, one’s sibling’s husband, or one’s spouse’s sibling’s husband, and sister-in-law for the one’s spouse’s sister, one’s sibling’s wife, or one’s spouse’s sibling’s wife.[2]

Just like other affines, or “in-laws”, siblings-in-law are related by a type of kinship called affinity. Just like the children of one’s siblings, the children of one’s siblings-in-law are called simply nieces and nephews – if necessary, specified whether “by marriage”, as opposed to “by blood” or “by adoption”.

One study, examining the issue of envy in the triadic system of sibling, sibling-in-law and spouse, concluded that “The sibling-in-law relationship shared similarities with both spousal and sibling relationships” and that “Relational closeness and satisfaction for all relationships in the triad were correlated.”[3]

In Islamic law (shariʿa)[4] and Jewish law (halakhah)[5] sexual relations between siblings-in-law are prohibited as incestuous, unless the spouse is no longer married. Conversely, in Judaism there was the custom of yibbum, whereby a man had a non-obligatory duty to wed his deceased brother’s childless widow so she might have progeny by him.[6]

If one pair of siblings is married to another pair of siblings, the siblings-in-law are thus doubly-related, each of the four both through one’s spouse and through one’s sibling, while the children of the two couples are double cousins.