News Release

Best predictor of arrest rates? The 'birth lottery of history'

Study finds social context of when one comes of age a bigger deal than socioeconomics

Peer-Reviewed Publication

Harvard University

Social scientists have had a longstanding fixation on moral character, demographic information, and socioeconomic status when it comes to analyzing crime and arrest rates. The measures have become traditional markers used to quantify and predict criminalization, but they leave out a crucial indicator: what's going on in the changing world around their subjects.

An unprecedented longitudinal study, published today in the American Journal of Sociology, looks to make that story more complete and show that when it comes to arrests it can come down to when someone is rather than who someone is, a theory the researchers refer to as the birth lottery of history.

Harvard sociologist Robert J. Sampson and Ph.D. candidate Roland Neil followed arrests in the lives of more than 1,000 Americans as they transitioned out of adolescence to being young adults over a 23-year span. This was a time period that saw some of the largest social change in recent memory, and the results indicate how these changes, which included the rise of mass incarceration, aggressive policing tactics, and the mid-1990s sudden drop in crime that became known as the "great American crime decline" -- helped shape how these adolescents and young adults came into contact with the criminal justice system.

"What we're attempting to do is to look at birth cohorts who were coming of age at different times during these social changes," said Sampson, Henry Ford II Professor of the Social Sciences. "The setting is roughly the last quarter-century or so. We focused on that because it's a time of great social change in the United States. Mass incarceration comes to the top of many people's minds, but we also saw a rise in violence before that and then a large decline in violence over most of the past 25 years. We saw tremendous changes in policing practices, and most recently, concerns about police brutality and police killings have risen."

What Sampson and Neil tried to do is link those changes with what it's like to grow up when it comes to criminalization, particularly arrest -- the trigger generating a criminal record in the first place. It sheds new light on the arrest patterns of people who came of age in different eras of the war on drugs, mass incarceration, and plummeting violence starting in the 1990s.

The researchers based their work on a multi-cohort longitudinal study of 1,057 children who were originally enrolled in a National Institute of Justice study called the Project on Human Development in Chicago Neighborhoods, a study of how families, schools, and neighborhoods affect child and adolescent development. The oldest individuals tracked were born between 1980 and the mid-1980s and were ages nine, 12, and 15 at the start of the study. The youngest in the study were born in 1995. All participants were tracked from 1995 to 2018.

All participants in the study, originally all Chicagoans, were followed over the course of nearly twenty-five years as they came of age. They were selected randomly based on a representative sample reflecting the diversity of contemporary urban America. Blacks and Latinos each comprised over a third of the sample while white participants made up 20 percent. More than a third of the individuals came from immigrant families. The researchers also collected information through interviews with caretakers and the participants over multiple rounds of data collection. It allowed Sampson and Neil to dig deep into the characteristics of the participants, their families, and early-life neighborhood conditions.

They used data based on criminal history records that were collected through the end of 2018 for all participants, allowing them to study arrest over a 23-year span. The analysis showed large differences in patterns of arrest among the four age cohorts across substantial portions of their lives "We wanted to know not only if there were differences in arrest rates for the different cohorts, but why were there differences," Neil said. "Do these differences reflect fundamental differences in who these people were, or differences in what happened early on in their life? Or did they reflect differences in the larger context through which they were aging?"

The researchers found it was the latter. In many cases, for example, even people who shared the same kind of character traits, grew up in similar families, and came from similar economic backgrounds had much higher or lower chances of getting arrested depending on the years during which they were 17 to 23 years old, the peak ages for arrest.

For instance, younger cohorts (those born in the 1990s) came of age during a radically different and, in some ways, more peaceful world than the older cohorts, who were born in the 1980s. In fact, the chances of arrest for the older cohorts were nearly double -- 96 percent higher -- than the younger cohorts, according to the study.

"The explanation for this can't just be reduced to the usual suspects -- childhood experiences, family structure, demographics, social class, family upbringing -- or individual characteristics," Sampson said.

This is where the birth lottery of history comes in, meaning the fortune of when they were born factored into their chances of arrest. Analysis showed just how significant a few years of social changes can make when it comes to arrest rates by looking at what are often cited as the two leading explanations for crime: socioeconomic disadvantage and having low self-control.

Approximately 70 percent of children born in the 1980s to disadvantaged families were arrested by their mid-20s while only about a quarter of disadvantaged children born in the mid-1990s were arrested by that same age. For participants from more advantaged backgrounds changes were moderate. Looking at those same cohorts, the study found that those born in the 1980s with higher self-control had about the same arrest rates as those born in the 1990s with low self-control.

"We should really be looking at not what was virtuous or wrong with individuals of a particular cohort but rather looking at what's right or wrong with the larger social environment during the historical period in which they happen to come of age," Sampson said. "This study is showing that historical changes are built into those very criminal records."

Changing law enforcement patterns explained about half the cohort differences in criminalization, with disorderly conduct and drug arrests falling substantially in the period they studied. However, the researchers make clear that these differences were not driven by aggressive policing alone.

They believe behavioral changes caused by larger societal changes also led to lower arrests for younger cohorts. For example, from the mid-90s to 2018, parts of urban Chicago underwent revitalization, gentrification, repopulation, and saw an influx of immigrants. In more recent years the rise of technologies such as smartphones, video games, the internet, and social media have also transformed the lives of young people, potentially reducing time spent in risky situations for arrest.

"Put simply, our results show that when we are matters as much and perhaps more than who we are or even what we have done. To the extent that arrest is a result of substantial social changes in both criminal justice practices and societal norms that strongly differentiate the life experience of successive birth cohorts, independent of individual or family differences, the idea of an individual's propensity to crime needs reconsideration," Sampson said.

The study pointed out potential caveats such as the study being limited to people originally from Chicago and only looking at 20 years of a person's life.

The researchers hope to expand their theory and the data they collected on cohort inequalities in criminalization. They plan on doing new interviews and continuing to add to the records they've built to dig into the data further.


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