Kevin Lewis

March 29, 2020

Differential fertility makes society more conservative on family values
Tom Vogl & Jeremy Freese
Proceedings of the National Academy of Sciences, forthcoming


Data from the General Social Survey indicate that higher-fertility individuals and their children are more conservative on “family values” issues, especially regarding abortion and same-sex marriage. This pattern implies that differential fertility has increased and will continue to increase public support for conservative policies on these issues. The association of family size with conservatism is specific to traditional-family issues and can be attributed in large part to the greater religiosity and lower educational attainment of individuals from larger families. Over the 2004 to 2018 period, opposition to same-sex marriage and abortion was 3 to 4 percentage points more prevalent than it would have been were traditional-family conservatism independent of family size in the current generation. For same-sex marriage, evolutionary forces have grown in relative importance as society as a whole has liberalized. As of 2018, differential fertility raised the number of US adults opposed to same-sex marriage by 17%, from 46.9 million to 54.8 million.

The Intergenerational Transmission of Early Educational Advantages: New Results Based on an Adoption Design
Andrew Halpern-Manners et al.
Research in Social Stratification and Mobility, forthcoming


Sociological research has traditionally emphasized the importance of post-birth factors (i.e., social, economic, and cultural capital) in the intergenerational transmission of educational advantages, to the neglect of potentially consequential pre-birth endowments (e.g., heritable traits) that are passed from parent to child. In this study, we leverage an experiment of nurture — children who were adopted at birth into nonrelative families — in an effort to simultaneously model the effects associated with both pathways. To do so, we fit a series of simple linear regression models that relate the academic achievement of adopted children to the educational attainments of their adoptive and biological parents, using U.S. data from a recent nationwide sample of birth and adoptive families (the Early Growth and Development Study). Because our dataset includes both “genetic” and “environmental” relatives, but not “genetic-and-environmental” relatives, the separate contributions of each pathway can be identified, as well as possible interactions between the two. Our results show that children's early achievements are influenced not only by the attainments of their adoptive parents, but also the attainments of their birth parents — suggesting the presence of environmental and genetically mediated effects. Supplementary analyses provide little evidence of effect moderation, using both distal and proximate measures of the childhood environment to model gene-by-environment interactions. These findings are robust to a variety of parameterizations, withstand a series of auxiliary checks, and remain intact even after controlling for intrauterine exposures and other measurable variables that could compromise our design. The implications of our results for theory and research in the stratification literature, and for those interested in educational mobility, are discussed.

The effect of California's paid family leave policy on parent health: A quasi-experimental study
Bethany Lee et al.
Social Science & Medicine, forthcoming


The U.S. is the only high-income country without a national paid family leave (PFL) policy. While a handful of U.S. states have implemented PFL policies in recent years, there are few studies that examine the effects of these policies on health. In this study, we tested the hypothesis that California's PFL policy — implemented in 2004 — improved parent health outcomes. Data were drawn from the 1993–2017 waves of the Panel Study of Income Dynamics, a large diverse national cohort study of U.S. families (N = 6690). We used detailed longitudinal sociodemographic information about study participants and a quasi-experimental difference-in-differences analytic technique to examine the effects of California's PFL policy on families who were likely eligible for the paid leave, while accounting for underlying trends in these outcomes among states that did not implement PFL policies in this period. Outcomes included self-rated health, psychological distress, overweight and obesity, and alcohol use. We found improvements in self-rated health and psychological distress, as well as decreased likelihood of being overweight and reduced alcohol consumption. Improvements in health status and psychological distress were greater for mothers, and reductions in alcohol use were greater for fathers. Results were robust to alternative specifications. These findings suggest that California's PFL policy had positive impacts on several health outcomes, providing timely evidence to inform ongoing policy discussions at the federal and state levels. Future studies should examine the effects of more recently implemented state and local PFL policies to determine whether variation in policy implementation and generosity affects outcomes.

Sibling Spillovers: Having an Academically Successful Older Sibling May be More Important for Children in Disadvantaged Families
Emma Zang, Poh Lin Tan & Philip Cook
Yale Working Paper, February 2020


This paper examines causal sibling spillover effects among socially advantaged (e.g. white, two-parent, or non-poor school district) and disadvantaged families (e.g. black, single-mother, or poor school district) in elementary and middle school. Exploiting discontinuities in school starting age created by North Carolina school entry laws, we adopt a quasi-experimental approach and compare test scores of public school students whose older siblings were born shortly before and after the school entry cutoff date. We find that individuals whose older siblings were born shortly after the school entry cutoff date have significantly higher scores in middle school, and that this positive spillover effect is particularly large among disadvantaged families. We estimate that these spillover effects account for more than one third of observed statistical associations in test scores between siblings, and the magnitude is much larger for disadvantaged families than advantaged families. Our results suggest that educational spillover effects from older to younger siblings lead to greater divergence in academic outcomes between families.

Children’s exposure to spatial language promotes their spatial thinking
Marianella Casasola et al.
Journal of Experimental Psychology: General, forthcoming


Does spatial language contribute to the growth of preschool children’s spatial skills? Four-year-old children (N = 50) were randomly assigned to a play-only (n = 24) or a spatial-language and play condition (n = 26). Their mental rotation and spatial vocabulary were assessed at baseline and several days after 5 play sessions. Children in the spatial-language condition scored higher at posttest on a mental rotation task than those in the play-only condition. The amount and diversity of experimenter spatial language during the play sessions accounted for a significant amount of the variance on children’s posttest mental rotation. Significant gains in mental rotation were replicated in a second study (N = 34) with a broader range of play activities and with children enrolled in Head Start. These results show that the facilitative effects of spatial language on spatial cognition are not restricted to the context in which the spatial language is provided. In particular, 4-year-old children’s experience with spatial language during play can transfer to promote their mental rotation.

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