Modeling Opportunity in America: The Success Sequence and Social Genome Model

In my new book, The Forgotten Americans, I revisit what has come to be called “the success sequence.” That’s the idea that if a young person gets a decent education (at least high school), works full-time, and finds a committed partner to marry before having children, that person’s chances of achieving the American dream of a middle-class income or better are high, while the chances of ending up poor are very low.

Critics of the success sequence note two flaws. The first is that the relationships may not be causal. Second, what is true in a one-year cross-section might not be true if one used longitudinal data and looked at the entire life cycle. Recent research by W. Bradford Wilcox and Wendy Wang has partially addressed both of these flaws in the earlier work done by myself and Ron Haskins. They find that 86% of Millennials (ages 28 to 34) achieve at least middle-class status if they follow the success sequence and that all but 3% of them avoid being poor. Because they control for many other possibly confounding variables and follow one cohort for a number of years, their work is also responsive to earlier criticism. Still, not everyone has completed their family formation by their late twenties, and much remains to be discovered about why various groups (such as racial minorities or children from lower-income families) who follow the success sequence, although clearly helped, don’t do as well as their more advantaged peers.

One way we might learn even more is by looking more deeply into children’s life trajectories. That motivated me to create a life-cycle model that follows children from birth to age 40, tracking an individual’s outcomes at the end of each of six life stages, and predicting how many children will be middle class by middle age (as well as their lifetime incomes) based on their characteristics and their success during all earlier life stages. (For more details, go here.) We call it the Social Genome Model, and it is now a partnership between Brookings, Child Trends, and the Urban Institute, with most of the current work to improve the data and the model being conducted at the latter two think tanks.

What have we learned from this model thus far? Three findings stand out:

First, consistent with the broader research literature on social mobility, a child’s circumstances at birth matter a lot for later success. We measure circumstances at birth by looking at the mother’s marital status, education, and income along with the child’s birth weight. The mother’s education is particularly important. It is likely a marker of her SES and her children’s genetic endowments. It may affect her parenting skills, neighborhood choice, attitudes toward education, ability to devote extra time or resources to her children, and a variety of social connections later in life (e.g. a college legacy preference). Being born black is a big handicap. This likely reflects current or past discrimination that makes it difficult for blacks to succeed at every stage of life. Being born female doesn’t hurt much during the school years when girls actually perform better than boys on most of our metrics, but it does create a modest drag on income during one’s adult years. All of these results persist after controlling for many other variables. However, we cannot rule out problems in the data or the model that lead to these findings.

Second, it’s clear that success is a cumulative process. According to our measures, a child who is ready for school at age five is almost twice as likely to be successful at the end of elementary school as one who is not. Those who can read well at age 9 are more likely to graduate from high school than those who cannot. Those who graduate from high school are more likely to graduate from college and so forth. This doesn’t mean that the child’s life course is set in stone. Children who get off the “success track” at an early age frequently get back on track at a later age; it’s just that their chances are not nearly as good. This seems to me to be a powerful argument for intervening early in life since success in each earlier stage affects success later on.

No single program does very much to close the gap between children from lower- and higher-income families. But the combined effects of multiple programs—that is, from intervening early and often in a child’s life—have a surprisingly big cumulative impact. 

Third, we can simulate how a change in any one variable in the model affects children’s life trajectories and also look at the impact of a variety of social programs on those trajectories. In one illustrative simulation, we chose a battery of rigorously evaluated programs where we knew the effects of the program on children’s outcomes (usually from a randomized control trial, or RCT) at different life stages. The interventions we examined included a parenting program, a high-quality early-education program, a reading and socio-emotional learning program in elementary school, and an effective high school reform. We then used the model to assess the possible impact on low-income children of taking these programs to scale.

No single program does very much to close the gap between children from lower- and higher-income families. But the combined effects of multiple programs—that is, from intervening early and often in a child’s life—have a surprisingly big cumulative impact. The initial gap of almost 20 percentage points in the chances of low-income and high-income children reaching the middle class shrinks to 6 percentage points. In other words, we were able to close about two-thirds of the initial gap in the life chances of these two groups of children by providing the less advantaged with a set of effective interventions from birth to age 18. The black-white gap narrows, too.

Looking at the cumulative impact on adult incomes over a working life and comparing these lifetime income benefits to the costs of the programs, we believe that such investments would pass a cost-benefit test from the perspective of society as a whole. It would also pass the test from the narrower perspective of the taxpayers who fund the programs since the higher incomes earned by the treatment group would enable them to pay higher taxes and be less dependent on government assistance.

In my new book, I focus primarily on work rather than on the other two pillars in the success sequence (family and education). Work is a core value in American society, and the decline in wages and employment among the less educated, especially less-educated men, is creating a host of problems from less stable families to distressed communities and high rates of addiction. Moreover, looked at from an annual accounting period, work does the heavy lifting in the success sequence. But this emphasis on work should not detract from the importance of both families and education to individual success over the entire life-cycle. They remain the early, and perhaps the most important, determinants of opportunity in America.

Isabel Sawhill is a Senior Fellow at the Brookings Institution and author of The Forgotten Americans: An Economic Agenda for a Divided Nation, Yale University Press, 2018. Portions of this essay are drawn from that book.