Tents, wheelchairs, and shopping carts piled with belongings sat baking in the sun next to the intersection where Kathryn Paige Harden pulled to a stop at a red light. She had driven past the homeless encampment, beneath an Austin freeway, often enough that she carried bottles of water to hand out through her car window to those who lived there. On this hot summer afternoon a couple years ago, her two young children voiced their concerns for the welfare of the camp’s residents. “Will ghosts get them at night?” the kids asked from the back seat. “Why don’t they have houses?”

Harden was struck by the range of potential answers to the latter question. They’d made bad choices? They didn’t work hard enough? The system was stacked against them? She gave her son and daughter the short version of what she believes: “Some people are unlucky in their lives.” 

She offers a much longer, more complex answer in her new book, The Genetic Lottery: Why DNA Matters for Social Equality, published this September by Princeton University Press. A psychologist at the University of Texas at Austin, Harden studies how our genes influence the way we think, feel, and act—a field known as behavioral genetics. She writes that some people are born lucky, with DNA containing variants that predispose them to academic achievement, stable jobs, higher incomes, and greater well-being. Others inherit variants more likely to lead to mental illness, addiction, and poverty, as well as a greater risk of homelessness. While acknowledging the roles our environment and experiences play in shaping our lives, Harden
makes the case that social scientists who want to address the roots of inequality must reckon with genetics.

That stance has made her something of a lightning rod. She’s been accused of promoting eugenics, the discredited pseudoscience of “improving” the human race through selective breeding. One colleague even likened her research to the claims of those who deny that the Holocaust occurred.

Harden isn’t a natural contrarian who delights in ruffling feathers. Being accused of sympathizing with Nazis stings. “There’s a stereotype of the academic who’s more interested in ideas than people and doesn’t care what people think. That doesn’t resonate with me,” she told me on a Zoom call from Bozeman, Montana, where she was spending the summer as a visiting professor at Montana State University. “I care what people think about me and my work. I’m interested in changing how people think.”

That’s what compelled her to write the book, despite any hostility it might provoke. She’s concerned about a “tacit collusion” among many of her fellow social scientists to exclude genetics from their research, motivated in part by fear. “There’s so much embedded in the public imagination about the gene,” she said. “They say, ‘If we find genes that are associated with traits we care about, like academic ability, doesn’t that open the door to social control?’ But that’s what psychology does, even when genes aren’t involved. We identify things that are associated with going further in school or being less likely to have depression.”

The more researchers understand about the myriad factors that influence how our lives turn out, the more they can help improve outcomes for everyone. Genetics is one of those factors, Harden argues: when we ignore it, the most vulnerable suffer. 

Kathryn Paige Harden speaking at a podium.
Kathryn Paige Harden participates in a debate hosted by the nonprofit Intelligence Squared, about the roles of parenting and genetics in child outcomes, in New York City in 2019.Samuel Lahoz/Intelligence Squared U.S.

If the genetic lottery shapes both our physical traits and our personalities, Harden’s ticket resulted in her being tall and slender, with expressive green eyes, a warm smile, and a thoughtful manner. She grew up in Tennessee, the daughter of an airline pilot and a schoolteacher. A merit scholarship took her to Furman University, a small liberal arts college in South Carolina, and she went on to earn her PhD in clinical psychology from the University of Virginia. Now 39, Harden runs the Developmental Behavior Genetics Lab, at UT, and is codirector of the Texas Twin Project, a long-term study of the effects of nature and nurture in twins. Like most psychologists, Harden believes both nature and nurture play crucial roles in determining our physical and behavioral attributes.

Early on, her research focused on identifying physiological markers of stress—primarily levels of the hormone cortisol—in children living below the poverty line. It proved expensive and time-consuming, and the results were not what she expected. “We had kids spit in a tube three or four times a day to measure their diurnal cortisol levels, and there were no differences in children’s cortisol profiles based on socioeconomic status,” she said. Yet her lab discovered a relationship between socioeconomic status and a process called methylation, which can alter the way genes are expressed. Children raised in poverty showed a troubling indicator of faster biological aging.

“It’s a distressing result in the sense that you’re already seeing these markers of poor health and disease in children, but it’s exciting in that it allows you to quantify one of the social determinants of health,” Harden said. “We have this vague idea that poverty gets under the skin to affect people’s health, but actually coming up with a biological tool to quantify that in children has been a challenge.”

Her lab now studies the genetic roots of risky behaviors—including
early sexual activity, drug and alcohol use, and juvenile crime—among children and teenagers. To make meaningful connections between genetic variations and corresponding traits, the researchers draw upon huge repositories of DNA profiles and social surveys collected in biobanks. Thanks in part to the growing popularity of genealogy companies such as Ancestry.com and 23andMe, these banks have amassed troves of genetic data from hundreds of thousands of people.

Over the past decade, new techniques have led to advances in analyzing the genetic components of both physical and behavioral traits, including those that help predict how happy, healthy, and prosperous each of us will be. For instance, a 2018 study published in the journal Nature Genetics, by an international team of researchers, parsed the DNA data of 1.1 million people around the world and found more than one thousand gene variants associated with how many years of school a person completes. The degree to which these variants were present was as strongly correlated with the likelihood of finishing college as was parental income—a highly significant link by social science standards.

What’s more, in a study published in Nature Genetics earlier this year, Harden and her colleagues used advanced statistical methods to find gene variants correlating to traits other than intelligence that affect educational success, such as grit, curiosity, motivation, and openness to new experiences. The results confirmed to Harden that the so-called “bootstrap mentality”—the belief that anyone can rise above adversity with enough hard work and determination—is fundamentally flawed. If grit and resilience are at least partly determined by genetics, then children can’t simply will those qualities into existence. That’s one reason she gets frustrated when developmental psychologists avoid any consideration of genetics. Mapping the DNA of schoolchildren could help us better equip them to overcome challenges, she says.

Plenty of social scientists disagree. Richard Lerner, the director of the Institute for Applied Research in Youth Development, at Tufts University, calls the use of genetics to predict educational outcomes “dangerous nonsense.” Studies that attribute behavioral differences to the combined effects of individual genes look impressive but ultimately explain little, he argues, and any interventions based on them are likely ineffective—and possibly much worse.

“These assertions have a long and sad history in the U.S. and elsewhere of damaging the lives of millions of marginalized young people,” he said, pointing to debunked theories from the heyday of eugenics that led to writing off entire groups of people from birth—including false claims that some races are inherently less intelligent or less ethical.

Catherine Bliss, a sociologist at Rutgers University and the author of Race Decoded: The Genomic Fight for Social Justice, is also wary of the existing research on genes and educational achievement. She notes that the findings often depend on surveys in which participants report their own outcomes—not always consistently—and that many of these studies come from a relatively small group of researchers. “In the wider science community, we don’t consider something a finding until unrelated researchers have replicated it. Certainly not a finding that you can base a whole educational system on,” she said.

Critics also point out that the studies conducted by Harden and other behavioral geneticists don’t establish causation, only correlation. “You can’t take these studies and say, ‘Here are the genes for good academic performance.’ There are no such things as ‘genes for’ anything, including height or eye color, let alone a complex thing like academic performance,” said David S. Moore, a developmental neuroscientist at Pitzer College, in Claremont, California. “Genes are inert. They don’t do anything independently of the contexts they’re in. Characteristics like eye color and height, even if they’re highly heritable, can also be dramatically influenced by environmental factors.”

Yet correlation is a valuable finding in its own right, Harden argues. “Correlations are a way to quantify our intuition about the relationships we’re seeing in the world,” she said. “It’s putting a number on that intuition, just like the correlation between family income level and college completion. It’s not all-or-nothing: Many affluent children have struggled in school, and poor children have done well. It’s neither destiny, nor is it useless—it’s this middle ground. That’s true with genetic correlations too. It’s not deterministic, but it tilts the playing field.”

Many of us recoil from the suggestion that our individual achievement could have genetic roots—with good reason. Similar ideas have been weaponized to appalling ends. The eugenics-motivated horrors of Nazi Germany tend to overshadow other examples, but the United States has its own shameful history of embracing genetic hierarchies.

In 1922 the American eugenicist Harry H. Laughlin published a proposal encouraging states to prevent procreation by “socially inadequate” individuals. Those were, in his words, the feeble-minded, insane, criminalistic, epileptic, inebriate, diseased, blind, deaf, deformed, or dependent, including “orphans, ne’er-do-wells, the homeless, tramps, and paupers.” The Nazi regime passed a 1933 law authorizing forced sterilizations, based in part on Laughlin’s proposal—but Virginia did so even earlier, sterilizing inmates of state institutions to prevent them from passing on their genes. Over the next half century, more than 60,000 Americans were sterilized in 32 states with similar statutes. Texas wasn’t among them, but it wasn’t entirely immune to the siren song of eugenics either. For example, in the early twentieth century, the State Fair of Texas hosted “Better Baby” contests in which judges awarded $15 to the “best” child, based on eugenic ideals of fitness.

Given humanity’s grim track record, it’s hard not to wonder if we can be trusted with behavioral genetic research. Its findings could be twisted to justify racial discrimination, as data on intelligence was in The Bell Curve, the controversial 1994 book by Charles Murray and Richard Herrnstein, which posited that “Latino and black immigrants are, at least in the short run, putting some downward pressure on the distribution of intelligence.”

Another fear that crops up is that genetic discoveries will result in custom-designed, gene-edited children. In the past decade, a technology called CRISPR has made it easier to alter DNA sequences, but Harden says that even if researchers wanted to build a super-baby, that isn’t as simple a matter as cutting out “bad” variants and pasting in “good” ones. To use a science-fiction analogy, editing DNA could have a “butterfly effect”: one tiny change in the sequence could have unintended consequences. Researchers have, for instance, discovered that some of the same genetic variants that correlate with high educational achievement are also linked to mental illnesses, such as schizophrenia.

Despite its current limitations, however, genetic research has the potential to offer illuminating insights, and no one benefits if those insights remain in the dark, said Michael Meaney, a McGill University neurobiologist. Meaney specializes in neurodevelopment, as well as epigenetics—the study of how our experiences and environment affect the ways in which our genes are expressed.

“This notion of, ‘I don’t like this data, and I’m just not going to deal with it’—that’s not going to get you anywhere,” he said. “Our ultimate goal in the social and health sciences is to mobilize the resources we have to those who are most in need. If I can help identify who’s most in need, using genetic tools as one tool in the shed, then I’ve rendered a service.”

Harden’s suggestion that genetics could identify children at greater risk of dropping out of school—and perhaps lead to effective interventions—isn’t fundamentally different from doctors identifying people at risk of heart disease, according to Meaney. He notes that the rate of premature mortality from heart disease declined by 70 percent from 1968 to 2017. “We did that by being able to predict who’s truly vulnerable,” he said. “It’s meant to be preventive. I’ve said nothing about determinism; I’ve said nothing about who’s better or who’s worse. You’re not a worse human being because you’re more likely to have heart disease.”

Still, having schoolkids spit into tubes in order to classify them according to their genetic variants may sound unsettlingly akin to Gattaca, a sci-fi film in which people are registered as “valids” and “in-valids” according to their genes. Labeling some students as high-risk based on their DNA and treating them differently as a result seems wrong. But Meaney points out that we already do something like this based on nongenetic factors. “If I’m a teacher and I have a child in my class whose family is undergoing some real disruption, I’m probably going to apply some level of sensitivity to that child that I wouldn’t apply to another child,” he said. “I don’t see anything wrong with that.”

If genetic research leads to initiatives that are as effective at getting students to finish school as are those aimed at preventing heart disease, Harden believes, we might narrow the gap in life outcomes that the “genetic lottery” creates. She’s seen how unequally it can play out, even in her own children. While her daughter spoke effortlessly early on, her son barely talked as a toddler. By the age of eight, he was undergoing hours of intensive speech therapy each week. Harden knows from her research that speech problems are more than 90 percent heritable. Her son was born with a set of genes that predisposed him to struggle with speech, while her daughter’s DNA made it possible for her to be linguistically gifted. But unlike eugenicists, Harden believes no one deserves credit—or blame—for their genetic inheritance.

“It would be very strange to say that my daughter did anything to earn her verbal precocity,” she writes in The Genetic Lottery. “Her speaking in complex sentences at an early age doesn’t make her good. If anything, the praiseworthiness belongs to my son, who brings the same deliberate, effortful attention to breath support and intonation to his daily conversations as an opera singer brings to a performance at the Met.”

Like all humans, Harden’s kids have equal intrinsic worth. They can’t be ranked. In her view, understanding the genetic factors that could make life harder for one of them means being able to give them both a fair shot at success.

Jennifer Latson is a Houston-based journalist and the author of The Boy Who Loved Too Much, a nonfiction book about a rare genetic disorder that makes people irrepressibly friendly.

This article originally appeared in the September 2021 issue of Texas Monthly with the headline “The Luck of the Genetic Draw.” Subscribe today.