Threats of mass deportations loom on the post-2024 election horizon. Some supporters claim these will protect the country from immigrants who bring " bad genes " into America. But this is a misguided use of the language of science to give a sheen of legitimacy to unscientific claims.
Author
- Shoumita Dasgupta
Professor of Medicine, Assistant Dean of Diversity & Inclusion, Boston University
Politicians invoke genetics to confirm false stereotypes that immigrants are more violent than native-born citizens as a result of biological differences. This is despite the fact that immigrants living in the country with or without legal authorization have significantly lower crime and violent crime rates than U.S. citizens. Moreover, there is no strong genetic evidence to support a biological predisposition for committing violent acts.
As a geneticist and a child of immigrants, I study the intersection of biology and bias. I am also author of the book " Where Biology Ends and Bias Begins: Lessons on Belonging from Our DNA ." What is clear from my professional work is that this line of thinking - attempting to use science to explain human difference in ways that reinforce social hierarchies - isn't new. It takes the playbooks of genetic essentialism and scientific racism and applies them to public policy.
The fallacy of genetic essentialism
Genetic essentialism is the concept that genes alone are the reason why someone develops a specific trait or behaves a certain way. For instance, a genetic essentialist would say that a person's athleticism, intelligence, personality and a range of other traits are encoded entirely in their DNA. They ignore the influence that sports training, material resources and learned behaviors have on these traits.
When used to explain differences between populations, genetic essentialism discounts the role that structural biases - inequities deeply ingrained in how systems operate - play in individual differences. Structural biases create a playing field that advantages one group over another from the start.
For instance, studies seeking to identify a gene for violent behavior may use measurements that are themselves biased. If arrest or incarceration rates were used as evidence of violence, study findings would be affected by discriminatory practices in the policing and criminal justice systems that more harshly penalize people of color.
Studies trying to disentangle the relative effects of genetic and structural factors on specific traits also face similar biases. For example, mental health outcomes are influenced by the identity-related stress that racial or sex and gender minorities experience. Similarly, socioeconomic outcomes are affected by the effects of redlining and segregation on generational wealth.
Genetics of educational attainment
As another example of behavioral genetics, consider a 2018 study on the genetics of educational attainment - in other words, whether certain genes were associated with years of schooling completed. The researchers were careful to communicate their results as pertaining specifically to educational attainment. They highlighted that genetic scores explained only about 11% to 13% of the variance - meaning, 87% to 89% of differences in educational attainment were due to influences other than genetics.
However, some popular press coverage oversimplified their findings as identifying genes for intelligence, even though the scientists did not directly measure intelligence - nor is it possible to.
Educational attainment can reflect everything from generational wealth to racial biases in education. A student with access to tutors their parents paid for has fewer educational obstacles than a student who has to work after school to make ends meet. Likewise, school punishment practices that are biased against students from certain backgrounds can set them on a harmful trajectory known as the school-to-prison pipeline .
Genetic studies are not conducted in a vacuum, and social influences can confound analyses seeking to focus on biological effects. In fact, some scientists think of genes as potential controls to allow more careful study of the nongenetic factors accounting for the remaining 87% to 89% of differences in educational attainment.
Intentional misinterpretation of these observations on educational attainment have led some to conclude that Black students are simply not as intelligent as their white counterparts. They argue that these differences are genetically encoded and immutable. However, when the effects of wealth gaps and school segregation are accounted for, test score gaps substantially narrow. Importantly, educational attainment gaps actually invert, predicting that Black students complete more years of school than white students.
Slipping to scientific racism
This brings us to scientific racism : the way in which science is contorted to support preexisting views about the superiority of the white race over all others.
American physician Samuel Morton was one of the original forebears of scientific racism. He was interested in providing "evidence" to support his belief that Caucasians were the most intelligent of all races. To do this, he collected skulls and categorized them into five racial groupings he believed were derived from separate creation events. He measured skull volume as an indicator of intelligence.
When comparing the averages from each group, his results supported his original theory. However, if he had instead focused on the array of skull volumes in his collection, he would have seen substantial overlap in each of the groupings. That is, each group had a range of small to large skulls. Morton's singular focus on proving his beliefs from the outset likely influenced his favored analytical approach. Nor is there a meaningful correlation between brain volume and intelligence.
Similar beliefs are at play when white supremacists manipulate data to create a scientific basis for their claims that white people are more intelligent than Black people. These tampered results appear in dark corners of the internet where they are shared in fringe journals, far-right social media memes and racist manifestos.
To be clear, there is no evidence that genetic differences related to intelligence or cognitive performance exist between racial groups. Instead, this is another argument growing out of replacement theory , the conspiracy theory that Jews and Western elites are deliberately replacing white populations with populations of color. Adherents believe that people of color are genetically inferior but are reproducing and immigrating at greater rates, and so threatening white power.
Human genetic variation
Scientists have systematically studied human genetic variation for decades, looking at differences in the DNA of people around the world. These studies definitively demonstrate that we are far more alike than different. The vast majority of common genetic variation is found across populations, and very few rare variants are specific to an individual group.
This may seem unexpected. Looking at the world around you, you'll observe some differences between racially defined groups, such as skin tone and hair texture. However, there is no place in the world where you'll be able to draw a line that cleanly separates people with dark skin tone from those with light skin tone. Skin color varies continuously across the globe, and a range of skin tones are present within any individual group.
Importantly, variation in one genetic trait is not predictive of other genetic traits . That is, you can't extrapolate conclusions about traits such as disease predisposition from the genes that influence 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 not be possible to connect an observed skin tone to predicted intelligence.
Misappropriating genetics
While science does not support genetic essentialism or other underpinnings of replacement theory, this exact rationale has made its way into national immigration policy.
These policies grew directly out of the American eugenics movement , which sought to build a supposedly better human race through social engineering based on "race science." Zoologist Charles Davenport created the Cold Spring Harbor Eugenics Record Office in 1910 to pursue his interests in evolution, breeding and human heredity. There, he and his colleagues collected records of American families, documenting their traits and ascribing genetic bases to them.
Harry Laughlin, a high school teacher Davenport recruited to serve as superintendent of the office, was later appointed as the expert eugenics agent for the U.S. congressional Committee on Immigration and Naturalization. He commissioned studies to document race-based trends in so-called biological traits such as intelligence, inventiveness and feeble-mindedness, erroneously concluding that observed patterns were due to genetic differences between populations. His findings were used to inform U.S. immigration quotas , which were set higher for populations deemed to have good genes and lower for those with undesirable traits.
These policies were codified in the Immigration Restriction Act of 1924 . In signing the act, President Calvin Coolidge declared, "America must remain American," paraphrasing a popular Ku Klux Klan slogan. This law severely restricted immigration from Asia and implemented strict quotas for immigrants from Southern and Eastern Europe. It also established elements of immigration that remain in 2025, including the visa system and the Border Patrol. With the passage of the Immigration Restriction Act, anti-Semitism and xenophobia became law of the land.
Coming full circle, genetic essentialism and racism continue to drive present-day rhetoric using " bad genes " to justify mass deportations of people deemed harmful to American society. Politicians and tech moguls are employing a combination of racism, willful misunderstanding of genetic science and political power to promote their own social agendas .
Politicians and hate groups have often weaponized genetics , leading to violent events carried out in the name of white supremacy. These include the 2017 Charlottesville Unite the Right rally , the 2019 Christchurch shootings of Muslims at two mosques, and the 2022 Buffalo massacre of Black customers at a neighborhood grocery store.
A better understanding of science and history can empower scientists, policymakers and others to reject unscientific claims and protect vulnerable members of society targeted by racism.
Shoumita Dasgupta does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
