Findings

Passed down

Kevin Lewis

June 30, 2019

Beyond the Great Recession: Labor Market Polarization and Ongoing Fertility Decline in the United States
Nathan Seltzer
Demography, forthcoming

Abstract:
In the years since the Great Recession, social scientists have anticipated that economic recovery in the United States, characterized by gains in employment and median household income, would augur a reversal of declining fertility trends. However, the expected post-recession rebound in fertility rates has yet to materialize. In this study, I propose an economic explanation for why fertility rates have continued to decline regardless of improvements in conventional economic indicators. I argue that ongoing structural changes in U.S. labor markets have prolonged the financial uncertainty that leads women and couples to delay or forgo childbearing. Combining statistical and survey data with restricted-use vital registration records, I examine how cyclical and structural changes in metropolitan-area labor markets were associated with changes in total fertility rates (TFRs) across racial/ethnic groups from the early 1990s to the present day, with a particular focus on the 2006-2014 period. The findings suggest that changes in industry composition - specifically, the loss of manufacturing and other goods-producing businesses - have a larger effect on TFRs than changes in the unemployment rate for all racial/ethnic groups. Because structural changes in labor markets are more likely to be sustained over time - in contrast to unemployment rates, which fluctuate with economic cycles - further reductions in unemployment are unlikely to reverse declining fertility trends.


Testing for family influences on obesity: The role of genetic nurture
John Cawley et al.
Health Economics, July 2019, Pages 937-952

Abstract:
A large literature has documented strong positive correlations among siblings in health, including body mass index (BMI) and obesity. This paper tests whether that is explained by a specific type of peer effect in obesity: genetic nurture. Specifically, we test whether an individual's weight is affected by the genes of their sibling, controlling for the individual's own genes. Using genetic data in Add Health, we find no credible evidence that an individual's BMI is affected by the polygenic risk score for BMI of their full sibling when controlling for the individual's own polygenic risk score for BMI. Thus, we find no evidence that the positive correlations in BMI between siblings are attributable to genetic nurture within families.


Thinking about multiple identities boosts children's flexible thinking
Sarah Gaither, Samantha Fan & Katherine Kinzler
Developmental Science, forthcoming

Abstract:
Studies of children's developing social identification often focus on individual forms of identity. Yet, everyone has multiple potential identities. Here we investigated whether making children aware of their multifaceted identities - effectively seeing themselves from multiple angles - would promote their flexible thinking. In Experiment 1, 6‐7‐year‐old children (N = 48) were assigned to either a Multiple‐Identities condition where they were led to consider their multiple identities (e.g., friend, neighbor) or to a Physical‐Traits condition where they considered their multiple physical attributes (e.g., legs, arms). Children in the Multiple‐Identity condition subsequently expressed greater flexibility at problem solving and categorization than children in the Physical‐Traits condition. Experiment 2 (N = 72) replicated these findings with a new sample of 6‐7 year‐old children and demonstrated that a multiple‐identity mindset must be self‐relevant. Children who were led to think about another child's multiple identities did not express as much subsequent creative thinking as did children who thought about their own multiple identities. Experiment 3 (N = 76) showed that a multiple‐identity framework may be particularly effective when the identities are presented via generic language suggesting that they are enduring traits (in this case, identities depicted as noun phrases rather than verbal phrases). These findings illustrate that something as simple as thinking about one's identity from multiple angles could serve as a tool to help reduce rigid thinking, which might increase open‐mindedness in a society that is becoming increasingly diverse.


When Behavioral Barriers are Too High or Low - How Timing Matters for Parenting Interventions
Kalena Cortes et al.
NBER Working Paper, June 2019

Abstract:
The time children spend with their parents affects their development. Parenting programs can help parents use that time more effectively. Text-messaged-based parenting curricula have proven an effective means of supporting positive parenting practices by providing easy and fun activities that reduce informational and behavioral barriers. These programs may be more effective if delivered during times when parents are particularly in need of support or alternatively when parents have more time to interact with their child. This study compares the effects of an early childhood text-messaging program sent during the weekend to the same program sent on weekdays. We find that sending the texts on the weekend is, on average, more beneficial to children’s literacy and math development. This effect is particularly strong for initially lower achieving children, while the weekday texts show some benefits for higher achieving children on higher order skills. Results are consistent with the hypothesis that the parents of lower achieving students, on average, face such high barriers during weekdays that supports are not enough to overcome these barriers, while for parents of higher achieving students, weekday texts are more effective because weekdays are more challenging, but not so difficult as to be untenable for positive parenting.


Older paternal ages and grandpaternal ages at conception predict longer telomeres in human descendants
Dan Eisenberg et al.
Proceedings of the Royal Society: Biological Sciences, May 2019

Abstract:
Telomere length (TL) declines with age in most human tissues, and shorter TL appears to accelerate senescence. By contrast, men's sperm TL is positively correlated with age. Correspondingly, in humans, older paternal age at conception (PAC) predicts longer offspring TL. We have hypothesized that this PAC effect could persist across multiple generations, and thereby contribute to a transgenerational genetic plasticity that increases expenditures on somatic maintenance as the average age at reproduction is delayed within a lineage. Here, we examine TL data from 3282 humans together with PAC data across four generations. In this sample, the PAC effect is detectable in children and grandchildren. The PAC effect is transmitted through the matriline and patriline with similar strength and is characterized by a generational decay. PACs of more distant male ancestors were not significant predictors, although statistical power was limited in these analyses. Sensitivity analyses suggest that the PAC effect is linear, not moderated by offspring age, or maternal age, and is robust to controls for income, urbanicity and ancestry. These findings show that TL reflects the age at the reproduction of recent male matrilineal and patrilineal ancestors, with an effect that decays across generations.


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