Parental Greatness
Modeling and Measuring the Genetic Determinants of Child Development
Francesco Agostinelli & Zach Weingarten
NBER Working Paper, October 2025
Abstract:
The longstanding debate over whether human capabilities and skills are shaped more by "nature" or "nurture" has been revitalized by recent advances in genetics, particularly in the use of polygenic scores (PGSs) to proxy for genetic endowments. Yet, we argue that PGSs embed not only direct genetic effects but also indirect environmental influences, raising questions about their validity for causal analysis. We show that these conflated measures can mislead studies of gene-environment interactions, especially when parental behavior responds to children's genetic risk. To address this issue, we construct a new latent measure of genetic risk that integrates individual genotypes with diagnostic symptoms, using data from the National Longitudinal Study of Adolescent to Adult Health linked to restricted individual SNP-level genotypes from dbGaP. Exploiting multiple sources of variation -- including the Mendelian within-family genetic randomization among siblings -- we find consistent evidence that parents compensate by investing more in children with higher genetic risk for ADHD. Strikingly, these compensatory responses disappear when genetic risk is proxied by the conventional ADHD PGS, which also yields weaker -- and in some cases reversed -- predictions for long-run outcomes. Finally, we embed our latent measure of genetic endowments into a standard dynamic structural model of child development. The model shows that both parental investments and latent genetic risk jointly shape children's cognitive and mental health development, underscoring the importance of modeling the dynamic interplay between genes and environments in the formation of human capital.
The Price of Parenthood: Childcare Costs and Fertility
Abigail Dow
Boston University Working Paper, October 2025
Abstract:
Across the developed world, fertility rates have fallen below replacement level, raising concerns over shrinking workforces and ageing populations. U.S. birthrates have reached historic lows, and high childcare costs pose a financial barrier to parenthood. This paper studies how childcare prices shape fertility decisions -- whether to have children, when to have them, and how many to have. Using an instrumental variables approach that exploits changes in U.S. state-level childcare regulations that effectively shift the price of childcare, I find that higher prices reduce birth rates, delay first births, and lengthen the interval between first and second births. A 10% increase in the price of childcare leads to a 5.7% decrease in the birth rate (4 births per 1000 women). Reduced form results show that changes in the regulations directly impact birthrates. Declines are largest amongst women aged 30 and above. I propose a theoretical model to explain this age gradient: older women earning higher wages face a greater opportunity cost of their time and thus outsource childcare, making them more sensitive to its price. Consistent with the model's predictions, older parents spend more on formal childcare, and more educated women (with higher incomes) exhibit greater price sensitivity. Additionally, older mothers are more likely to be considering higher order births, which I find to be more price sensitive.
Build, Baby, Build: How Housing Shapes Fertility
Benjamin Couillard
University of Toronto Working Paper, November 2025
Abstract:
Many developed countries face low and falling birthrates, potentially affected by rising costs of housing. Existing evidence on the fertility-housing cost relationship typically uses geographic variation (raising selection issues), neglects unit size, and says little about policy. To progress on these fronts, I first specify a dynamic model of the joint housing-fertility choice allowing choices over location and house size, estimated using US Census Bureau data. I extend 'micro-moment' techniques (Petrin, 2002; Berry et al., 2004a) both to circumvent data constraints and to incorporate heterogeneous residuals, which can prevent misspecification. Housing choice estimates confirm a Becker quantity-quality model's predictions: large families are more cost-sensitive, and so rising housing costs disincentivize fertility. To study the causal effect of rising housing costs on fertility, I vary them directly within the model, finding that rising costs since 1990 are responsible for 11% fewer children, 51% of the total fertility rate decline between the 2000s and 2010s, and 7 percentage points fewer young families in the 2010s. Policy counterfactuals indicate that a supply shift for large units generates 2.3 times more births than an equal-cost shift for small units: family-friendly housing is the more important policy lever.
Comparing the Role of Selection in Early Adolescent Substance Use Disparities Related to Single-Mother Family Structures Across Three Affluent Countries
Jared Thorpe & Robert Crosnoe
Demography, October 2025, Pages 1661-1687
Abstract:
This study investigated the association between family structure and the onset of substance use by early adolescence (e.g., before age 14) in Australia, the United Kingdom, and the United States, with a focus on the role of selection in this association. Leveraging nationally representative surveys, logistic regression models estimated this association while iteratively controlling for three sets of selection mechanisms and testing for differential robustness to unobserved traits. Results revealed higher substance use rates among early adolescents living with single mothers than among those living with married mothers; early adolescents living with cohabiting mothers fell between these two groups. In general, mothers' family formation histories and, especially, socioemotional adjustment emerged as key confounds attenuating these associations, whereas their socioeconomic histories more often suppressed substance use. Unobserved confounds also appeared to be at work. Such patterns were fairly consistent across countries, but some evidence suggests that single motherhood mattered more to early adolescent substance use (particularly alcohol) and was less selective in terms of observed and unobserved confounds in Australia, the country with the most policy buffers for families and youths facing hardship.
The Impact of Maternal Mortality Improvements on the Baby Boom
Christopher Handy & Katharine Shester
Washington and Lee University Working Paper, September 2025
Abstract:
Between 1936 and 1957, fertility rates in the U.S. increased 62 percent and the maternal mortality rate declined by 93 percent. We explore the effects of changes in maternal mortality rates on white and nonwhite fertility rates during this period, exploiting contemporaneous or lagged changes in maternal mortality at the state-by-year level. We estimate that declines in maternal mortality explain 47-73 percent of the increase in fertility between 1939 and 1957 among white women and 64-88 percent of the increase in fertility among nonwhite women during our sample period.
Does Increasing Financial Access to Contraception in the U.S. Reduce Undesired Pregnancies? Evidence from the M-CARES Randomized Control Trial at Two Years
Martha Bailey et al.
NBER Working Paper, October 2025
Abstract:
We use a randomized controlled trial to examine how the costs of contraception affect method choice, pregnancy, abortion, and childbirth among U.S. women. The study recruited women seeking care through Title X -- a national family planning program subsidizing reproductive health services for low-income Americans -- and randomized vouchers making the full spectrum of available contraception highly discounted or free. We find that subsidizing contraception has large and persistent effects on the choice of contraceptive method, resulting in significantly fewer pregnancies and abortions within two years. Subsidizing contraception negatively affected births, but the effect was not significant at two years.