“We analysed Hitler’s DNA – and what we discovered made us gasp”

Few historical figures have been discussed and debated as much as Adolf Hitler. We have a wealth of primary source material available to us about his life, including his autobiographical manifesto Mein Kampf, personal correspondence, political directives and military orders, recordings and transcripts of his countless speeches, eyewitness accounts, photographs and film footage.

Now, 80 years after his death, Hitler's DNA: Blueprint of a Dictator, a groundbreaking documentary produced by Blink Films and currently airing on Channel 4, has unlocked a new source by presenting the results of a world-first analysis of a sample of Hitler’s DNA. The DNA was taken from the blood on a small piece of fabric cut from the sofa on which Hitler died after shooting himself in his Berlin bunker on 30 April 1945

We have the privilege of being part of this documentary – both as lead investigators and in our separate roles as senior historical consultant (Alex) and the person leading the genetic analysis (Turi). The background to the documentary was a multi-stage process, each step a powerful marrying of genetics with history.

It probably goes without saying that the first step was to confirm that the blood sample was actually that of Hitler. With this in mind, it’s important to remember that, as in any forensic case, DNA evidence cannot be taken in isolation. It has to be combined with other types of evidence, in this case reaching back into the past for information first about Hitler’s suicide and then about how the piece of fabric came to be available for DNA testing.

The Führer’s family tree

So, what does the history tell us? With the Red Army closing in, Hitler killed himself in his Berlin bunker on the afternoon of 30 April 1945. In the days following his death, the Soviets controlled access, and few people were allowed in. Among those who were permitted to enter was Lieutenant Colonel Roswell P Rosengren, public information officer for General Dwight D Eisenhower, the supreme Allied commander in Europe.

While taking various souvenirs, Rosengren cut out a swatch of the fabric on the sofa on which Hitler had shot himself – and which, crucially, was stained with blood. He took it home to the United States and kept it under lock and key, before passing it down to his son. It was later acquired by the Gettysburg Museum of History in Pennsylvania, which in turn offered it for DNA analysis to anyone who was interested. Accompanying the swatch was a signed affidavit from Rosengren’s son confirming its provenance. Certainly, the fabric looked like it matched photographs of the sofa. So far so good.

Next came the genetic analysis for the identification. It is standard in cases such as this to analyse the DNA from the sample and compare it either with a previous authenticated sample from the individual in question or with the DNA of a close relative. Yet there were no such close relatives available to carry this out: Hitler had no children. However, as part of a previous study, more than a decade ago, a journalist called Jean-Paul Mulders and a genealogist named Marc Vermeeren had traced distant male-line members of Hitler’s family tree living in Europe and had obtained DNA from one of them.

Mulders had been particularly interested in tracing male-line members of Hitler’s family tree because there is a segment of DNA that is passed down through the male line: the Y-chromosome. Y-chromosome types differ between individuals, but male-line members of the same family tree should carry identical, or near-identical, Y-chromosome types. Analysing the Y-chromosome type from a male-line relative gives you, essentially, Hitler’s Y-chromosome type. All these years later, if the blood on the piece of fabric was from Hitler, the Y-chromosome from it should match that from the relative whose DNA had already been tested.

This was a huge moment in the project. So you can imagine our relief when we established that there was a DNA match – and, what’s more, it was a rare Y-chromosome type. Still, here historical context is, again, important. What were the chances of a male-line relative having access to the bunker and, crucially, also bleeding on the sofa? Given the rarity of the Y-chromosome type and what we know about the whereabouts of Hitler’s few male-line relatives at the time, the chances of this happening were vanishingly small. The blood sample, and thus the DNA in it, belonged to Hitler. We had his DNA.

Sequencing the genome

The match led to another of the study’s major discoveries: an answer to the question of whether Hitler had Jewish heritage through his paternal grandfather. In view of Hitler’s virulent antisemitism and his pivotal role in the extermination of 6 million European Jews, it is understandable that this particular rumour has triggered a great deal of speculation among both scholars and the general public alike. Well, the rigorous scientific testing carried out for the documentary has now confirmed beyond doubt what serious historians had long believed: namely that there is no truth in a rumour that has circulated since the early 1920s. The DNA match firmly debunks the Jewish ancestry myth.

The next step was to sequence the entire genome. Hitler now joins thousands of historical individuals – often nameless but including among their number the famous German composer Ludwig van Beethoven – whose genomes have been sequenced. We approached the task with an open mind. But given how many medical biographers have tried to diagnose Hitler from a distance, we were naturally interested in what the former German leader’s DNA could tell us about his health.

But first, let us be clear about what Hitler’s DNA can tell us – and, more importantly, what it cannot. This calls for a quick genetics lesson. For some diseases and conditions, the process is straightforward. Known as monogenic in origin, the development of a given condition can be traced back to a single gene or genetic variant that affects how the gene is working or, in this case, not working. A common example of a single gene disorder is cystic fibrosis.

However, for other conditions and diseases, it is a far more complex picture, because they are both polygenic and multifactorial. This means that many – often hundreds – of genetic variants are involved, each incrementally increasing or decreasing a person’s risk of developing the condition. What’s more, the risk of developing the condition is also influenced by environmental factors ranging from chemical exposure (such as smoking) to lifestyle (such as diet). A common example of one of these conditions is coronary artery disease.

A shock revelation

We analysed the DNA in two ways: by sending the genetic results to experts in different fields so that they could identify any medical conditions of interest; and also by running it through the standard medical pipelines for known genetic variants associated with various conditions. The results were striking.

First, thanks to the work of colleagues at the Pasteur Institute in Paris, we found that Hitler had a well-known deletion in a gene that is associated with Kallmann syndrome and the elaborately named Congenital hypogonadotropic hypogonadism. While the severity can vary from person to person, this mutation can result, among other things, in an impaired testosterone production, low libido, abnormalities in the development of sexual organs, and, by extension, a disrupted reproductive function.

This was a gasp moment in the study, and of particular interest to historians. The revelation that Hitler had some form of Kallmann syndrome is intriguing because of the implications for his private life. The finding suggests there could have been a causal relationship between Hitler’s genetic make-up and particular facets of his behaviour. It complements what we already knew about this part of Hitler’s biography, and it sheds light on aspects of his life that we could previously only speculate about.

The finding suggests there could have been a causal relationship between Hitler’s genetic make-up and particular facets of his behaviour

A physical examination of Hitler, conducted during his incarceration in Landsberg prison in 1923 following the failed Munich putsch – but only known about since the rediscovery of the medical file in 2010 – revealed that he had “right-sided cryptorchidism”. That is, an undescended testicle. (It turns out that the British satirical song ‘Hitler Has Only Got One Ball’, the origins of which remain unknown, was close to the mark after all.)

“Some sense of shame”

This physical abnormality might help to explain an account given by August Kubizek, Hitler’s closest (and perhaps only) friend during his adolescence. Hitler and Kubizek shared a room in Vienna from February to July 1908. Noting Hitler’s “obvious indifference to the opposite sex”, his “strict monk-like asceticism” and the fact that he “refrained from masturbation”, Kubizek observed: “My friend undoubtedly found favour with the opposite sex although, to my amazement, he never took advantage of it.”

Commenting on the entirety of their friendship from the autumn of 1905, when they met at the opera in Linz, to the summer of 1908, when their time together in Vienna came to an end, Kubizek concluded: “I think I can say with certainty: Adolf never met a girl, either in Linz or Vienna, who actually gave herself to him.”

Tellingly, Ernst Hanfstaengl, one of Hitler’s closest confidants during the 1920s and 1930s, later wrote: “I can never recall having seen him in a bathing costume, nor had anyone else. A story, probably authentic, was frequently told that Hitler’s old army comrades, who had seen him in the wash-house, had noted that his genital organs were almost freakishly underdeveloped, and he doubtless had some sense of shame about displaying himself. It seemed to me that this must all be part of the underlying complex in his physical relations, which was compensated for by the terrifying urge for domination expressed in the field of politics.”

According to the historian Ian Kershaw, author of the definitive biography of Hitler, “Kubizek’s account, together with the language Hitler himself used in Mein Kampf, does point at the least to an acutely disturbed and repressed sexual development.” Rumours that Hitler had been infected with syphilis by a Jewish prostitute were without foundation: medical tests in 1940 showed that Hitler had not suffered from syphilis. The discovery that Hitler had Kallmann syndrome might thus be the key to explaining his seemingly “disturbed and repressed sexual development”.

Looking for patterns

Hitler may well have been extremely self-conscious about his body and, for this reason, reluctant to engage in relations of an intimate or sexual nature – and perhaps even uninterested in that side of life. This fact would help to explain his absolute devotion to politics to the almost complete exclusion of any kind of private life. Such devotion was exceptional among Nazi leaders. All other senior Nazis – Hermann Göring, Heinrich Himmler, Joseph Goebbels, Martin Bormann, Rudolf Hess, Albert Speer, and so on – had wives and children. Some even had extramarital affairs.

Ian Kershaw also wrote: “There was no ‘private life’ for Hitler. Of course, he could enjoy his escapist films, his daily walk to the Tea-House at the Berghof, his time in his alpine idyll far from government ministries in Berlin. But these were empty routines. There was no retreat to a sphere outside the political, to a deeper existence that conditioned his public reflexes.”

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The discovery and testing of Hitler’s DNA, combined with the historical facts already available to us, may explain why.

When testing the DNA sample, experts at Aarhus University in Denmark looked at more complex conditions such as neurodevelopmental and psychiatric disorders. When scientists are interested in a condition that is polygenic, they determine which genetic variants might predispose someone to the condition by looking, in a large population, at the patterns of DNA in people who have that particular condition compared to those who do not.

One can then take an individual’s DNA and place them, based on the genetic variants they carry, on the bell-curve distribution to see how they compare to others in that population. Do they have a lot of the genetic variants that seem to predispose someone to the condition, or very few? This is known as a polygenic score. Hitler’s results were, again, striking. His polygenic score placed him in the top 1 per cent for schizophrenia, for autism and for bipolar disorder.

However, we have to be really clear here: Hitler’s polygenic score being high is not diagnostic. We cannot, from his DNA, say that he would have been diagnosed with any of these conditions. Even people with the highest scores aren’t diagnosed with the disorder 95 per cent of the time. What makes Hitler so unusual is not the possibility that he might have had any one of these disorders on its own, but rather the fact that his placement in the top 1 per cent for the polygenic scores of all three of these conditions is exceptional: none of the other individuals in the population analysis had the same result. Still, we know that numerous environmental factors, such as adverse life events, would have had a big influence on his likelihood of developing them.

What’s more, it is important not to stigmatise people with these conditions. It is rare for anyone with any of these conditions to go on to commit violent acts, let alone genocide. Indeed, they are more likely to be on the receiving end of violence. Genetics is only one part of the puzzle in determining who someone will become.

Nature vs nurture

No attempt to explain the man Hitler became and the extreme inhumanity he exhibited can, therefore, be reduced to a question of genetics. But it is interesting to view these scores in light of what we already knew about him.

Environmental and social factors played a central role in moulding Hitler. Born in provincial Austria in 1889, he had a traumatic childhood, experiencing abuse at the hands of his father and losing four out of five siblings as well as both parents by the age of 19. He later wrote in Mein Kampf that the death of his mother, Klara, had been “a dreadful blow”. These events would have gone a long way toward shaping Hitler’s character, regardless of his genetic makeup.

Similarly important for the bigger picture is the fact that Adolf Hitler was only one man. He was the undisputed dictator of Germany for 12 years. He devised and ordered the genocide of Europe’s Jews, as well as countless other atrocities. But he did not act alone. There were hundreds of thousands of perpetrators, each with their own genetic makeup and life experiences. Millions more eagerly followed him and profited from his policies. Genetics does not bring us any closer to understanding and explaining how the Holocaust could have happened.

At the same time, it is undeniable that certain people have a huge and lasting impact on the course of historical events. Hitler is one of those people. Ian Kershaw once wrote of the dictator: “He is one of the few individuals of whom it can be said with absolute certainty: without him, the course of history would have been different.” Being able to analyse Hitler’s DNA thus offers us a remarkable opportunity to add another layer of information in the quest to understand more about the man regarded as “the embodiment of modern political evil” (Kershaw). However, we want to emphasise that it is not possible to see evil in someone’s DNA.

A new piece of the puzzle

It can be argued that only under Hitler could the Nazis have come to power, consolidated that power, waged a European war and committed the most terrible crimes in modern history. One reason for this is Hitler’s single-mindedness in the pursuit of power, which was unmatched by any other senior Nazi. That he had some form of Kallmann syndrome could well have been a factor in his renunciation of any kind of private life or intimate relationships. All available evidence suggests that he did not even have sex with his long-term companion, Eva Braun. Hitler always claimed that his life was devoted to Germany, so that there was no room in it for a wife. It seems this claim might, at least in part, have been a way of covering up his aversion to intimate relationships, and that his genes could have played a more significant role in his decision not to marry (until the day before his death) and not to have children than he was willing to admit.

Hitler always claimed that his life was devoted to Germany, so that there was no room in it for a wife

No single piece of evidence explains everything. We cannot take the genetic information about Hitler in isolation. It needs to be couched within our knowledge of what DNA can and cannot tell us, but crucially also within what we know about Hitler, and the time in which he lived. A rare constellation of factors – genetic, environmental and societal – all contributed to the emergence of Hitler. The discovery of his DNA – and the findings that have emerged from its analysis and are now presented in this cutting-edge documentary – provide historians with a rare and extremely significant new piece of the jigsaw puzzle in their attempts to understand and explain the most notorious figure of the 20th century.

Turi King is the lead geneticist on the research into Hitler’s DNA. Alex J Kay is a historian specialising in Nazi Germany. Their groundbreaking work is covered in the two-part Channel 4 and Blink Films documentary Hitler’s DNA: Blueprint of a Dictator