Republican presidential nominee Donald Trump has repeatedly denounced immigrants who enter the U.S. illegally and the danger he says that poor immigrants of color pose for the U.S. – often using hateful language to make his point.

In early October 2024, Trump took his comments a step further when he questioned immigrants’ faulty genes, saying without support that “Many of them murdered far more than one person, and they are now happily living in the United States. You know, now a murderer, I believe this, it’s in their genes. And we got a lot of bad genes in our country right now.”

It was far from the first time Trump has invoked eugenics – a false, racist theory that some people, and even some races, are genetically superior to others.

In 1988, for example, Trump told Oprah Winfrey during an interview: “You have to be born lucky in the sense that you have to have the right genes.”

In 2016, Trump said that his German roots are the reason behind his greatness:

“I always said that winning is somewhat, maybe, innate. Maybe it’s just something you have; you have the winning gene. Frankly it would be wonderful if you could develop it, but I’m not so sure you can. You know, I’m proud to have that German blood, there’s no question about it. Great stuff.”

And in 2020, Trump again alluded to his belief that bloodlines convey excellence:

“I had an uncle who went to MIT who is a top professor. Dr. John Trump. A genius. It’s in my blood. I’m smart.”

Trump’s repeated and countless comments about white people’s racial superiority to people of color have prompted some comparisons to the Nazis and their ideology of racial superiority.

The Nazis are indeed the most infamous believers of the false idea that white, blue-eyed, blonde-haired people were superior to others – and that the human population should be selectively managed to breed white people.

But the Nazis didn’t originate these ideas. In fact, the Nazis were so impressed with many American eugenic ideas that they incorporated them into their racist, antisemitic laws.

Root of eugenics

The British scientist Francis Galton, a cousin of the evolutionist Charles Darwin, first developed the theory of eugenics in the 1860s, and it gained a foothold in the U.S. and Britain around this time.

Eugenics sets racial identity, and especially white identity, as the most desirable and worthy.

By the dawn of the early 1900s, much of the American eugenics scholarship looked down on American immigrants from any place other than Scandinavia, thus coining the term “Nordicism.”

In the late 19th and early 20th century, immigration to the U.S. was at its peak. In 1890, 14.8% of people living in the U.S. were immigrants. Many people felt concerned about immigration in the U.S., and there were many prominent eugenicists in America. Two of the most famous were Madison Grant and Lothrop Stoddard.

Both were avowed white supremacists who advocated for scientific racism. They wrote popular and widely read books that helped shape American and German law in the 1920s and 1930s.

Grant, Stoddard and other theorists in the U.S. embraced eugenics as a way to justify racial segregation, restrict immigration, enforce sterilization and uphold other systemic inequalities.

Stoddard attacked the United States’ immigration policies in his 1920 book, “The Rising Tide of Color: The Threat Against White World-Supremacy.” He wrote: “If the present drift is not changed, we whites are all ultimately doomed. … We now know that men are not, and never will be equal. We now know that environment and education can only develop what heredity brings.”

Another prominent eugenicist was Harry H. Laughlin, an educator and superintendent of the Eugenics Record Office, a now-defunct research group that gathered biological and social information about the American population.

Laughlin wrote an influential 1922 book, “Eugenical Sterilization in the United States,” which included a chapter on model sterilization laws. The Third Reich used his book and laws as a template when implementing them in Germany during the height of the Nazi period.

Laughlin also regularly testified before U.S. Congress, with this 1922 testimony representative of his message to lawmakers: “Immigration is essentially and fundamentally a racial and biological problem. There are many factors to consider, but, from the standpoint of the future, immigration is primarily a long time national investment in human family stocks.”

Eugenicists, including Laughlin, have long been specifically preoccupied with Norwegian genetics – believing that America is under attack when immigration occurs from non-Nordic countries.

In November 1922, Laughlin said, “Some of our finest and most desirable immigrants are from Norway.”

In 1924, Congress approved the Immigration Act, which severely limited immigration to the U.S., established quotas for immigrants based on nationality and barred immigrants from Asia.

It was only following the end of World War II and the Holocaust that eugenics fell out of favor and lost its prominence in American thinking.

Trump’s recycling of history

Fears over foreign immigrants weakening the U.S. were popular a century ago, and Trump and many of his followers still embrace them today.

Trump has promised that he will carry out mass deportations of immigrants living in the U.S. illegally, forcibly detaining immigrants in camps and removing 1 million people a year.

In April 2024, Trump used dehumanizing language to express his apparent belief that immigrants are unworthy of empathy. “The Democrats say, ‘Please don’t call them animals. They’re humans.’ I said, ‘No, they’re not humans, they’re not humans, they’re animals.’”

Trump has also promoted eugenicists’ obsession with Scandinavia and the superiority of white people.

In 2018, Trump spoke about immigrants from Haiti, El Salvador and Africa, saying “Why are we having all these people from shithole countries come here?”

In the same meeting, Trump also reportedly suggested that the U.S. should instead draw in more people from countries like Norway.

In April 2024, Trump again embraced this idea of Scandinavian superiority, saying that he wants immigrants from “Nice countries. You know, like Denmark, Switzerland? Do we have any people coming in from Denmark? How about Switzerland? How about Norway?”

A dangerous flash to the past

A person running for president in 1924 would seem more likely than a candidate in 2024 to espouse this now-discredited point of view.

President Calvin Coolidge ran for election on an “America First” platform in 1924, with the slogan only falling out of favor after groups like the Ku Klux Klan embraced it around the same time.

The idea of America First, at the time, denoted American nationalism and exceptionalism – but also was linked to anti-immigration and fascist movements.

When Coolidge signed the heavily restrictive 1924 Immigration Act into law he stated, “America must remain American.”

One hundred years later, Trump calls to mind an America First mentality, including when he regularly reads the lyrics to a song called “The Snake” during his rallies as a way to explain the dangers of welcoming immigrants into the U.S. The civil rights activist Oscar Brown wrote this poem in 1963, and his family has said that Trump misinterprets the song’s words.

‘I saved you,’ cried that woman.

‘And you’ve bit me even, why’

‘You know your bite is poisonous and now I’m going to die.’

‘Oh shut up, silly woman,’ said the reptile with a grin,

‘You knew damn well I was a snake before you took me in.’

I have written a book on this and I used many of my citations in Chapter 4 to help develop this piece though I reworded or reframed it.