Daughters-in-law and mothers-in-law in lowland rural Nepal: The balance of power and health outcomes.

Background and objectives: The relationship between daughters-in-law (DIL) and mothers-in-law (MIL) is often portrayed as conflictual, though from an evolutionary perspective, the two women could cooperate to gain Darwinian fitness benefits. We investigated this relationship in a society where it is central to women's social niche. Without asking directly, we aimed to evaluate markers of conflict and harmony in households, and whether variability in this balance was reflected in differential health outcomes. We also tested whether conflict was less likely in households with more children, and hence greater shared genetic interest.

Methodology: We studied 110 co-resident DIL-MIL dyads from rural lowland Nepal and compared anthropometry, physical and mental health, lived experience, agency, and attributed contributions to household tasks.

Results: Overall, DIL had better mental health than MIL, and greater weight and height. Tension over childcare and resting was common. Mental health and height differences within dyads were greater in households with inferred conflict over childcare, compared to inferred harmony households. DIL had better health outcomes and higher weight and height relative to MIL if they lived in conflict compared to harmony households, whereas MIL had better health outcomes if they lived in harmony households. Number of children did not predict conflict.

Conclusions and implications: Despite MIL being senior in the household, DIL reported lower stress and better mental health, especially in households with inferred conflict. DIL in such households also had better nutritional status. Having had time since marriage to consolidate their status in the household, DIL may have increased their agency and power.

Lay summary: Our study in rural Nepal aimed to identify which of daughter-in-law or mother-in-law held the upper hand in the household hierarchy, and how this was reflected in health outcomes. Although mothers-in-law are more senior, daughters-in-law had better physical and mental health, especially in households with inferred conflict over childcare.