Twin births are often construed as a natural experiment in the social and natural sciences on the premise that the occurrence of twins is quasi-random. We present population-level evidence that challenges this premise. Using individual data for 17 million births in 72 countries, we demonstrate that indicators of mother's health, health-related behaviors, and the prenatal environment are systematically positively associated with twin birth. The associations are sizable, evident in richer and poorer countries—evident even among women who do not use in vitro fertilization—and hold for numerous different measures of health. We discuss potential mechanisms, showing evidence that favors selective miscarriage.

This paper investigates the sensitivity of the intergenerational transmission of health to changes in the socioeconomic and public health environment into which children are born using individual survey data on 2.24 million children born to 600,000 mothers during the period 1970 to 2000 in 38 developing countries merged by country and cohort with macroeconomic data. We find that children are more likely to bear the penalty exerted by poor maternal health if they are conceived or born in adverse socioeconomic conditions. Equivalently, shocks to the child's birth environment are more damaging of children born to women with weaker health at birth.

We estimate impacts of male job loss, female job loss, and male unemployment benefits on domestic violence (DV) in Brazil. We merge individual-level employment and welfare registers with different measures of DV: judicial cases brought to criminal courts, the use of public shelters by victims, and mandatory DV notifications by health providers. Leveraging mass layoffs for identification, we first show that both male and female job loss, independently, lead to large, and pervasive increases in DV. Using a regression discontinuity design, we then show that access to unemployment benefits does not reduce DV while benefits are being paid, and it leads to higher DV risk once benefits expire. Our findings can be explained by the negative income shock brought by job loss and by increased exposure of victims to perpetrators, as partners tend to spend more time together after displacement. Although unemployment benefits partially offset the income drop following job loss, they reinforce the exposure shock as they increase unemployment duration. Since our results cannot be explained by prominent DV theories, we propose a simple model formalizing these mechanisms.

This paper examines policy effectiveness as a function of leader identity. We experimentally vary leader religious identity in a coordination game implemented in India and focus on citizen reactions to leader identity, controlling for leader actions. We find that minority leaders improve coordination, and majority leaders do not. Alternative treatment arms reveal that affirmative action for minorities reverses this result, while intergroup contact improves the effectiveness of leaders of both identities. We also find that minority leaders are less effective in towns with a history of intergroup conflict. Our results demonstrate that leader and policy effectiveness depend on citizen reactions, conditioned by social identity and past conflict.

We identify earnings impacts of exposure to an infant health intervention in Sweden, using individual-linked administrative data to trace potential mechanisms. Leveraging quasi-random variation in eligibility, we estimate that exposure was associated with higher test scores in primary school for boys and girls. However, only girls were more likely to score in the top quintile. Subsequent gains, in secondary schooling, employment, and earnings, are restricted to girls. We show that the differential gains for women accrued from both skills and opportunities.

We identify dynamic impacts on domestic violence (DV) of the staggered imposition and lifting of lockdown across Chile’s 346 municipalities. Lockdown increases DV helpline calls and shelter occupancy without increasing DV police reports. These results are consistent with lockdown raising incidence and creating barriers to reporting. Once lockdown is lifted, shelter occupancy falls and police reports surge, but helpline calls remain elevated in line with state dependence in DV. We identify male job loss as a mechanism driving DV. Our findings accentuate controversy around welfare impacts of lockdown mandates. Adverse impacts of lockdown on DV are mitigated by cash transfers.

We evaluate the medium-term impacts of treating maternal depression on women’s mental health, financial empowerment, and parenting decisions. We leverage variation induced by a cluster-randomized controlled trial that provided psychotherapy to 903 prenatally depressed mothers in rural Pakistan. It was one of the world’s largest psych otherapy interventions, and it dramatically reduced postpartum depression. Seven years after psychotherapy concluded, we returned to the study site to find that impacts on women’s mental health had persisted, with a 17 percent reduction in depression rates. The intervention also improved women’s financial empowerment and increased both time- and money-intensive parental investments by between 0.2 and 0.3 standard deviations.

The Nigerian civil war of 1967-70 was precipitated by secession of the Igbo-dominated south-eastern region to create the state of Biafra. It was the first civil war in Africa, the predecessor of many. We investigate the legacies of this war four decades later. Using variation across ethnicity and cohort, we identify significant long-run impacts on human health capital. Individuals exposed to the war at all ages between birth and adolescence exhibit reduced adult stature and these impacts are largest in adolescence. Adult stature is portentous of reduced life expectancy and lower earnings.

We introduce and validate a novel approach to identifying good managers. In a preregistered lab experiment, we causally identify managerial contributions by randomly assigning managers to teams and controlling for individual skill. We find that manager contributions are crucial for team success, and that people who self-select into management roles perform worse than randomly assigned managers. Managerial performance is strongly predicted by economic decision-making skill but not by demographic characteristics. Two validation studies support our experimental results. Participants who succeed in the lab receive more real-world promotions and, in a separate study of retail store managers, skill measures strongly predict store sales. A one standard deviation increase in manager quality increases annual per store sales by US$4.1 million (25% increase). Selecting managers on skills rather than demographic characteristics or the desire to lead could substantially improve organizational performance.