US men and women both reported more conflict with mothers-in-law than with mothers, and mothers reported more conflict with their daughters-in-law than with their daughters

Mother-in-Law Daughter-in-Law Conflict: an Evolutionary Perspective and Report of Empirical Data from the USA. Jessica D. Ayers, Jaimie Arona Krems, Nicole Hess & Athena Aktipis. Evolutionary Psychological Science, Jan 10 2022. https://link.springer.com/article/10.1007/s40806-021-00312-x

Abstract: Relationships with genetic relatives have been extensively studied in the evolutionary social sciences, but affinal, i.e., in-laws, relationships have received much less attention. Yet, humans have extensive interactions with the kin of their mates, leading to many opportunities for cooperative and conflictual interactions with extended kinship networks. To contribute to the scholarship on affinal bonds, and particularly on perceptions of affinal conflict, we collected empirical data on cooperation and conflict among affines. Here, we report empirical evidence of self-reported cooperative and conflictual aspects in affinal relationships in a Western sample. US men and women both reported more conflict with mothers-in-law than with mothers, and mothers reported more conflict with their daughters-in-law than with their daughters. We discuss the implications of this work and directions for future research.