Mass deportations don’t rule out “bad genes”—who use scientific racism to justify biased immigration policies

The threat of mass deportations looms after the 2024 election. Some proponents claim these will protect the country from immigrants bringing “bad genes” into the United States. But this is a misuse of scientific language, giving unscientific claims a sheen of legitimacy.

Politicians use genetics to confirm false stereotypes that immigrants are more violent than native-born citizens due to biological differences. This is despite the fact that immigrants living in this country, with or without legal authorization, have significantly lower crime and violent crime rates than U.S. citizens. Furthermore, there is no strong genetic evidence to support a biological predisposition to violent behavior.

As a geneticist and the child of immigrants, I study the intersection of biology and bias. I am also the author of Where Biology Ends and Prejudice Begins: Lessons from the Belonging of Our DNA. It’s clear from my professional work that this line of thinking—attempting to use science to explain human differences in order to reinforce social hierarchies—is not new. It takes the playbook of genetic essentialism and scientific racism and applies it to public policy.

The fallacy of genetic essentialism

Genetic essentialism is the concept that genes themselves are the reason someone develops certain traits or behaves in a certain way. For example, a genetic essentialist would say that a person's athletic ability, intelligence, personality, and a host of other characteristics are entirely encoded in their DNA. They ignore the effects of athletic training, material resources, and learned behaviors on these characteristics.

When used to explain differences between populations, genetic essentialism underestimates the role that structural biases (inherent inequalities in the way a system operates) play in individual differences. Structural bias creates a playing field that favors one group over another from the outset.

For example, studies seeking to identify genes for violent behavior may use measurements that are inherently biased. If arrest or incarceration rates are used as evidence of violence, findings will be affected by discriminatory practices in policing and criminal justice systems that punish people of color more harshly.

Studies that attempt to disentangle the relative contributions of genetic and structural factors to specific traits face similar biases. For example, mental health outcomes are affected by identity-related stress experienced by racial or gender minorities. Likewise, socioeconomic outcomes are affected by the effects of redlining and segregation on intergenerational wealth.

Genetics of educational attainment

As another example of behavioral genetics, consider a 2018 study on the genetics of educational attainment—in other words, looking at whether certain genes are associated with years of schooling completed. The researchers were careful to convey findings related to educational attainment. They emphasized that genetic scores explained only about 11% to 13% of the variance, meaning that 87% to 89% of the differences in educational attainment were due to influences other than genetics.

However, some popular media reports oversimplified their findings as identifying genes for intelligence, even though the scientists did not directly measure intelligence—and could not have done so.

Educational attainment can reflect everything from generational wealth to racial bias in education. Students who must work after school to make ends meet face fewer barriers to education than students whose parents pay for tutors. Likewise, punitive practices in schools that are biased against students from certain backgrounds can put them on a harmful trajectory, the school-to-prison pipeline.

Genetic research is not conducted in a vacuum, and social influences can confound analyzes seeking to focus on biological effects. In fact, some scientists consider genes a potential controlling factor, and the non-genetic factors responsible for the remaining 87% to 89% of the difference in educational attainment could be examined more closely.

Deliberate misunderstanding of these observations about educational attainment has led some to conclude that black students are simply not as smart as white students. They believe these differences are genetically encoded and unchangeable. However, when the effects of wealth inequality and school segregation are taken into account, the test score gap shrinks significantly. Importantly, the educational attainment gap is actually inverted, predicting that black students complete more schoolwork than white students.

The slide towards scientific racism

This brings us to scientific racism: science twisted to support pre-existing ideas about the superiority of the white race to all other races.

American doctor Samuel Morton was one of the founders of scientific racism. He is interested in providing “evidence” to support his belief that white people are the most intelligent of all races. To do this, he collected skulls and divided them into five racial groups, which he believed originated from different creation events. He measured skull volume as an indicator of intelligence.

When comparing the averages of each group, his results supported his original theory. However, if he focused on a series of skull rolls in his collection, he would see that there was considerable overlap in each grouping. That is, each group has a series of skulls ranging from small to large. Morton's focus from the beginning on proving his beliefs may have influenced his preferred analytical approach. There is also no meaningful correlation between brain size and intelligence.

Similar beliefs are at play when white supremacists manipulate data to create scientific evidence for their claims that white people are smarter than black people. These doctored results appeared in dark corners of the internet, shared in fringe journals, far-right social media memes and racist manifestos.

To be clear, there is no evidence of genetic differences between racial groups related to intelligence or cognitive performance. Rather, this is another argument stemming from replacement theory, the conspiracy theory that Jews and Western elites deliberately replace white people with people of color. Supporters argued that people of color were genetically inferior but reproduced and immigrated more quickly, thus threatening white power.

human genetic variation

For decades, scientists have systematically studied human genetic variation, observing differences in the DNA of people around the world. These studies clearly show that we are far more alike than we are different. The vast majority of common genetic variants are found across human populations, and few rare variants are specific to a group.

This seems unexpected. Take a look at the world around you and you will notice some differences between different racial groups, such as skin color and hair texture. However, nowhere in the world is there a clear distinction between dark-skinned people and light-skinned people. Skin color continues to vary across the globe, and different skin tones exist within any individual group.

Importantly, variation in one genetic trait does not predict other genetic traits. That is, you cannot infer conclusions about traits such as disease susceptibility from genes that affect skin color. Even if the fallacy of genetic essentialism were true and cognitive ability was primarily a biological trait (which it is not), it would be impossible to relate observed skin color to predicted intelligence.

Misappropriation of genetics

While science does not support genetic essentialism or other foundations of alternative theories, this exact rationale has found its way into national immigration policy.

These policies stemmed directly from the American eugenics movement, which sought to create a purportedly better human race through social engineering based on “racial science.” Zoologist Charles Davenport founded the Cold Spring Harbor Eugenics Records Office in 1910 to pursue his interests in evolution, breeding, and human heredity. There, he and his colleagues collected records of American families, documented their traits and attributed a genetic basis to them.

Harry Laughlin, a Davenport high school teacher, was hired as chief of staff and later appointed as the eugenics expert attorney to the U.S. Congressional Committee on Immigration and Naturalization. He commissioned studies documenting race-based trends in so-called biological traits (such as intelligence, creativity, and mental retardation) and incorrectly concluded that the observed patterns were due to genetic differences between populations. His findings are used to inform U.S. immigration quotas, which are higher for those considered to have good genes and lower for those with unfavorable traits.

These policies were codified in the Immigration Restriction Act of 1924. In signing the act, President Calvin Coolidge declared, “America must remain America,” a popular Ku Klux Klan slogan. The law severely restricted immigration from Asia and imposed strict quotas on immigrants from southern and eastern Europe. It also identifies elements of immigration that will remain in place through 2025, including the visa system and border patrol. With the passage of the Immigration Restriction Act, anti-Semitism and xenophobia became the law of the land.

Back to square one, genetic essentialism and racism continue to drive today’s discourse, using “bad genes” to justify mass deportations of people deemed harmful to American society. Politicians and tech moguls are exploiting a combination of racism, deliberate misunderstanding of genetic science, and political power to advance their own social agendas.

Politicians and hate groups often weaponize genetics, leading to violence in the name of white supremacy. These include the 2017 Unite the Right rally in Charlottesville, the 2019 shootings of Muslims at two mosques in Christchurch, and the 2022 massacre of black customers at a neighborhood grocery store in Buffalo.

A better understanding of science and history can empower scientists, policymakers, and others to reject unscientific claims and protect vulnerable members of society who are targeted by racism.