Did Hitler have a secret Jewish grandfather? Our DNA research has solved the mystery

Matt Elton, HistoryExtra: How did you get involved in this project and did you have any concerns?

Alex J Kay: I got involved in the project in March 2023. I was contacted by Dan Chambers from Blink Films, who had already been working on this project for quite some time. I knew that Turi was already involved and they were looking for a lead historian for the programme.

My big concern – because there’s so much out there about Hitler, so many documentaries, so many studies, so many books – was that this was going to be done in a serious way. Not sensationally, but really following the science, and very much based on research and evidence. Everybody who was involved with the project was clearly following science and really wanted to do a good job, and make sure it was as ironclad as possible in terms of the research and the evidence, so that reassured me.

Turi King: I was brought on almost exactly four years ago. My first question was around not wanting to be involved if this was going to be done in a sensationalist way. And I did agonise [over doing it] because of who it is. But then, as an ancient DNA specialist, there have been thousands of individuals, archaeological and historical specimens, who have had their whole genome sequenced – including Beethoven. And I was thinking: “Well, why should Hitler be seen as this kind of mystical figure whom we could never do this DNA analysis on? And who is it who makes those kinds of decisions?”

As Alex has said, Hitler has been the subject of so many books and articles and television programmes and so on, but this would add a new layer of information that hasn’t been available before. The other thing was that, because the swatch [a small sample of material] was being made available for DNA analysis, somebody was going to do this at some point, so let’s make sure it’s done in an absolutely rigorous way. My first question was: “Is this actually Hitler’s DNA?” My first role in this was to go through the entire process around authenticating the DNA.

So let’s talk about the swatch you mentioned there. Alex, can you talk about the final days of Hitler’s life and how they enabled the specific set of circumstances that allowed this research to happen?

AJK: Hitler spent the last weeks of his life in his Berlin bunker virtually the entire time, only occasionally going up into the garden of the Reich Chancellery building. By [April] the Soviets were attacking the city. The Red Army had already entered Berlin and was fighting its way to the city centre, where the government headquarters were and where Nazi power was based – and of course Hitler’s bunker as well. At some point, Hitler realised the war was definitively lost and the Soviets would reach him within a matter of days.

He took the decision to take his own life, which we know from eyewitness accounts he did by shooting himself, in his study on the now notorious sofa. It’s from this sofa that the piece of fabric was taken with the blood sample.

Who took the sample from the sofa? And why?

TK: So this was Colonel Roswell P Rosengren, who was a public information officer for Eisenhower during the war. The Red Army was in charge and apparently very few people were allowed to go into the bunker, but he was one of them. This was where Hitler had killed himself – so they got into the bunker and essentially started taking souvenirs. Rosengren cut a sample out of the sofa and took a swatch away – which, rather crucially, had blood on it from where Hitler killed himself.

Did he have any idea that it was likely to be Hitler’s blood?

TK: You would have to ask his family, but my understanding is that yes [he did]. The swatch was then brought back to the US and kept in the family for several decades. It was then passed down to his son, whom I had the pleasure of talking to, and who knew the entire story about how it had been brought into the family. Then, [in 2014] it was sold to the Gettysburg Museum of History. It was the museum that had been offering it for DNA analysis.

Why has all this happened now given that that sample was in this museum all this time?

TK: I think part of it [is a result of] genetic technology and what’s become available over the past 10–20 years. We are now able to do more and more in terms of sequencing. The field of ancient and historical DNA has really taken off, and we now have the ability to do this sort of work, which is why everything’s come together to make this happen.

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There were multiple objections from European institutions because they were uncomfortable with testing Hitler’s DNA. Did that cause you any concerns?

TK: Certain labs would have a think about it. They might go to their boards and they would say, “No, we don’t feel comfortable with doing this.” I’m Canadian and I have a lot of colleagues in the US, and I think for us the shadow of Hitler doesn’t feel as close as it must do to people here. That’s to do with geographical distance. In the end, the two labs that did the sequencing – because you want the sequencing done in two separate labs to make sure you’re getting the same results in both labs – are both in the US, where the sample is.

AJK: I wasn’t entirely surprised when I was told that a number of European labs had decided not to get involved. I’m based in Germany, and there is a lot of awareness of the long shadow that Hitler still casts here, even 80 years after his death. There’s a great reluctance to get involved with anything that could be used for sensationalist purposes or where somebody could distort the facts.

TK: One of the things that’s been really difficult about this project is trying to work to get an academic paper and the documentary to go out at the same time. It’s something over which I have no control, but there is an academic paper that I’m hoping will be able to come out in the next few weeks. That was one of the other things that I said when I first got involved: that there had to be an academic paper as well, it couldn’t just be a documentary.

How did you determine whether the sample that was taken stood up to scrutiny?

TK: This is where I always say it’s incredibly important that you don’t just use genetic data on its own, you link it with the historical information. My first question was, “What’s the provenance of this sample?” And actually, if you have a look at the photos of the sofa from the time period and then you look at the swatch, there’s a very distinctive pattern and those match. So that’s another tick we could put into the box.

The other thing we could then do is genetic analysis. But there were no very close relatives that you could use for doing DNA testing and comparing against, such as you would do in a forensic case – a parent or a sibling or a child. They don’t exist because Hitler didn’t have any children. There are no close relatives who are alive today. This is where I got interested in a piece of DNA known as the Y chromosome, a segment of DNA that’s just passed down through the male line.

So if there’s a male-line relative of Hitler, then you can look at the Y chromosome that’s coming back from the DNA, from the blood, and see if that matches a male-line relative. There was a study that had been done by Jean-Paul Mulders and Marc Vermeeren. They had tracked down quite distant members of the Hitler family, male-line members, including one who had given a DNA sample. The data from that was made available. We could then do an analysis of the Y chromosome and there was a perfect match between them.

The next thing you have to ask as a geneticist is, “Okay, but how common is this Y chromosome type?” And, actually, it’s incredibly rare, not found in the Y chromosome forensic database. Even then, because we were being careful as we went, we wanted to know how common it is in Europe, let alone worldwide. There were no hits, so we could therefore say: “Yes, it’s a rare Y chromosome type.”

And then we had to ask: “What is the likelihood that a close male-line relative of Hitler would have managed to get himself into the bunker, over to that sofa and bleed on it?” This is where Alex is great because I can turn to him and ask: “So what do we know about close male line relatives?” Once we can rule out all of these possibilities, it becomes vanishingly unlikely that this is not Hitler’s DNA.

AJK: Hitler had very few close male-line relatives. He had no surviving brothers, for example, and lost four of his five siblings during his childhood. The only other surviving child was his sister, Paula. He did have a half-brother from his father’s previous marriage. However, I was able to determine that his half-brother at the end of the war was in Hamburg, not Berlin, so that ruled him out.

This half-brother had two sons. One of those sons, however, had been killed in combat during the Second World War. So he was no longer alive in 1945, and the other son had actually emigrated and wasn’t even in the country. So we were able to rule out in this way that any other close male relative of Hitler’s could have been anywhere near the bunker in April 1945.

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Once you had started to become convinced that this might actually be Hitler’s DNA, what did that feel like?

TK: That was a bit of a moment because you can go: “Okay, great, we can be confident that we’ve got Hitler’s DNA.” The next stage then is to do the whole genome sequencing. But the thing about that was we genuinely had no idea what we would find. As a geneticist, you think: “Well, possibly he has a very boring genome where he has a slight genetic predisposition towards something like coronary heart disease.” We didn’t know at all what we were going to find.

Just before we get into what you found, what happened to Hitler’s body?

AJK: Hitler’s body was burnt. He gave very explicit instructions to some of his members of staff who were still in the bunker for his body to be doused in petrol and burnt so that no remains were left. Hitler was very concerned that he would fall into the hands of the Soviets, dead or alive.

Stories had been told to him about Mussolini’s death. Mussolini had been killed by Italian partisans and his corpse had then been strung up in a city square and abused by people – spat on and hit. Hitler wanted to avoid this demeaning fate, so he gave his members of staff in the bunker explicit instructions to get rid of his body, to destroy it completely. This didn’t happen: there were attempts made and the body was partially burnt, but not completely. Some bones did survive and the Soviets had access to those, but there was no body to speak of.

How big a factor is the degradation that happens to a sample such as this over time, and does it affect the validity of the results in any way?

TK: That’s a good question. One of the things I was actually looking [into] as part of the authentication processes was whether the DNA looks like it’s degraded. If it was a hoax, first of all, you wouldn’t get a DNA match but, secondly, the DNA would look quite different. While we’re alive we actually have really lovely long strands of DNA. And we do have things that come along and ‘nick’ it, but our body has mechanisms for fixing those DNA strands back together again. After death, that doesn’t happen. The DNA ends up in shorter and shorter strands, until there’s nothing left to sequence and the DNA is quite damaged.

People often have this idea that there is a time factor in terms of how long it would be that we are able to obtain DNA. It’s actually time, but also the conditions under which the sample has been kept. Cold and dry is best for preserving DNA, which is why you can have some samples that are only a few years old but, if they’ve been kept in warm and damp conditions, you can’t get DNA out of them. But with other samples, people have managed to get nearly 2 million-year-old DNA out of permafrost.

It was one of those things that, until we started the project and started having a look, we didn’t know quite whether or not the sample would be usable. The DNA is degraded, as would be expected, but we’ve got enough sequencing from two separate labs to get enough ‘coverage’ of the genome so that we can have a look at it. There are still gaps, but there’s enough that we can still do the analysis that we’ve been doing.

A key thing is that, when we started this project, it was very important to say – and still to say – that nothing that we could ever find in Hitler’s DNA would excuse what he did. If I can get that message across, I think that’s super-important because no matter what we found, it doesn’t excuse what Hitler did in his lifetime.

AJK: We’ve got to keep in mind that genetics, as Turi has just said, is only one small piece of the puzzle. Hitler was very much a product of his times, of the First World War and postwar revolution in Germany. He was a product of a particular political radicalisation that took place in Germany in the 1920s. He was also the product of a traumatic childhood, losing four of his five siblings and both his parents by the age of 19.

We have to keep in mind all of these factors when trying to understand the man Hitler became, and how it was possible for him to do what he did – and also in assessing how important these genetic findings are in the bigger picture. We’ve also got to emphasise that Hitler was a central figure in what then happened in the Second World War, and in the Holocaust, but he was only one man. There were hundreds of thousands of German and Austrian perpetrators [and other collaborators] who committed the most horrific crimes. There were many millions of people who followed Hitler and profited from the Nazi regime. We can’t explain what happened just by looking at Hitler and certainly not just by looking at Hitler’s genes.

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One of the claims the programme specifically debunks is the idea that Hitler might have had Jewish heritage. How did you go into looking into this and how specifically did you debunk it?

TK: I’m going to let Alex talk about the history here, but I can give you the genetics. So essentially my understanding is that there were queries about who Hitler’s paternal grandfather was. The story is that Hitler’s paternal grandfather wasn’t actually from the Hitler family and might have been Jewish because Hitler’s paternal grandmother was working in the house of a Jewish family at the time. The fact that we have a Y chromosome match between the blood and a distant male-line member of the Hitler family shows that Hitler’s grandfather was indeed from the Hitler family.

AJK: Rumours that Hitler might have had some Jewish ancestry have been around for the best part of a century. They were already circulating in the 1920s. Some people believed that his paternal grandmother, Maria Anna Schicklgruber, who had worked for a period of time in a Jewish household, had become pregnant as a result of that.

The foreign press got hold of these rumours and made a lot out of them. It’s very important that we’ve been able to debunk that, because this has been something that both scholars and the general public alike have been very interested in – understandably, because of Hitler’s rabid antisemitism and his crucial role in the extermination of 6 million European Jews. There’s no truth in the rumours. Hitler did not have Jewish ancestry.

Work also began on sequencing the entire genome of Hitler’s DNA. Before we talk about the potential this has for revealing new information about Hitler’s health, where do we need to be cautious when we’re talking about this kind of research?

TK: I think a genetics lesson here is important because, when you’re looking for a genetic predisposition towards particular health conditions, there are two types of health condition that you can look at. There are particular health conditions where we know it goes back to a single gene, so if something is wrong with a particular gene, you will develop this condition. And then there are other conditions where we know it’s both polygenic, meaning many genes, and also multifactorial. So genetics is just a component of the condition, but there are all kinds of other factors that are involved.

You could be genetically predisposed towards heart disease, for example. If you are being healthy, eating well and exercising, you’re less likely to go on to develop this than if you are sedentary, and you’re sitting on the sofa and you’re eating doughnuts all day. With things like smoking, chemical factors come into it, too, and we know that smoking makes you more likely to develop lung cancer, for example.

So when we were looking at these two particular types of conditions, what we were doing with Hitler’s DNA was, firstly, running it through standard NHS ‘pipelines’. But also, because there have been so many medical biographers over the past [few] years and also during his lifetime who had suggested particular conditions, we did send the DNA to experts in particular fields to ask “Is there anything here that stands out to you?”

This is where colleagues at the Pasteur Institute found there’s a deletion [a type of mutation where a part of a chromosome or a segment of DNA is lost] in a gene known as PROK 2, which is strongly associated with Kallmann syndrome, which has implications for testosterone levels and the development of sexual organs.

We also found that Hitler was in the top 1 per cent for polygenic scores for schizophrenia, bipolar and autism. It’s probably a good idea that I give a quick explanation about how polygenic scores work. So this is where geneticists say: “Right, we’ve got all of these people over here with this particular condition. What are the genetic variants that they seem to have in common with one another that these people over here without the condition don’t seem to have, or have at much lower frequencies?” What you can then do is take somebody’s DNA and ask: “Well, where do they sit on this particular distribution?” This was work done by the IPSYCH team in Denmark.

And this is where Hitler came in as being in the top 1 per cent for these three particular conditions – and that is incredibly rare.

This is one of the areas in which the documentary enters into territory where we need to be careful about what we’re talking about. Did either of you have concerns about making connections between Hitler and specific conditions, however delicately phrased and couched?

TK: That’s really important. In the documentary, what we do is we put all of the caveats in: we do talk about how this is not diagnostic just because he’s getting these scores. It is talking about a genetic predisposition, and you can’t run a straight line from this particular polygenic score to him being diagnosed with this particular condition. The other thing that’s very important to say is that it’s incredibly rare for people with these conditions to go on to commit violent acts, let alone genocide. They’re more likely to be on the receiving end of violence.

And as Alex was saying, Hitler was not active on his own. There were hundreds of thousands of people who were helping him. They’re not all going to have the same genetic makeup as one another. These caveats are really important to put out there. In the documentary, we’re clear we cannot say that he had any of these particular conditions, but there is a genetic predisposition towards them.

AJK: As a historian, I would say we have to approach this research like we would approach any other historical source, namely with care. We have to double-check it. We have to compare it against other sources of information, other evidence that we have, other things that we know. That would be the first step in any approach in dealing with this. And in this case, as Turi has already wonderfully explained, this is an indication of predisposition.

We do not know whether Hitler had any of these conditions. And therefore for me, the finding, while fascinating, is less important than the findings on potential Jewish ancestry – because we now know something definite, whereas with the polygenic scores the findings are merely an indication. I do think it’s striking, as Turi has said, that Hitler had this top 1 per cent predisposition in all three of these categories, but we’re not saying, “Oh, look, Hitler might have had one of these conditions” – it’s actually that he’s in the top 1 per cent for all three. Potentially, this kind of explosive mix makes it quite a quite remarkable finding, but it’s not proof of anything yet because it’s just an indication.

I would also say that we’re talking a lot about what responsibilities the makers of the programme have and the people involved in it. Both Turi and I, and everybody else involved in the programme, take these responsibilities very seriously. I also think, by the same token, that anybody watching this documentary and then commenting on it, particularly journalists reporting on it, equally has a responsibility to report on it in a serious way and to place it in context – not to emphasise one particular aspect to the exclusion of everything else, not to remove all the caveats that we have put in. That responsibility works both ways.

During the media frenzy of the past few days, and when some journalists have emphasised certain findings of the programme or certain indications in the programme to the exclusion of others, or when people have talked about the risk of stigmatisation, I have asked myself: “Would some people have preferred us not to reveal certain findings, just to reveal some findings but hold back other findings?” Surely, if we’d done that and it had come out at some point in the future, that would’ve been a good reason to reproach us?

TK: Just to echo what Alex has said, it’s been really interesting to see how some of the journalism has gone. You know, they haven’t bothered to take on board everything that Alex and I talk about, about how it’s so important that you take this in the context of what we know about DNA and in the context of the historical setting for all of this. And also to echo that our role is to lay out what we have found, and to put in all of the caveats about what we can and cannot say.

But again, as Alex was saying, if we held back information, that would be seen as kind of gatekeeping and elitist, and I would not feel comfortable with that. I think it would be inappropriate to withhold information.

Among the research findings is the fact that Hitler’s DNA bears evidence of a genetic mutation that in some cases can result in abnormalities, including a micro-penis. Lots of the more salacious reporting has focused on this. Given that, do you have any regrets about its inclusion and the fact it’s overshadowed the rest of the research?

TK: In the documentary and in the academic paper, we talk about how the DNA cannot tell us what Hitler’s genitalia looked like. All we can do is report that [a micropenis] is known to be strongly associated with Kallmann syndrome. He will have had some form of Kallmann syndrome.

These are various phenotypes, or ways in which the condition manifests itself in somebody. All we can do, again, is put the caveats in. And this is where Alex’s work is really important, because there are historical documents around what we already know about Hitler’s genitalia. It’s when you put the genetics and the history together that you get a better understanding of all this.

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AJK: It was slightly predictable, the way that some newspapers and some media outlets have reported on this. For me, it’s not particularly interesting what Hitler’s genitalia looked like. What is interesting is the discovery that he had Kallmann syndrome, which is a genetic disorder. It actually explains a lot about Hitler’s private life – or, more accurately, his lack of a private life, because Kallmann is associated with low testosterone levels, low sex drive, and it impacts on the development of the reproductive features and the reproductive functions. It tells us a lot about how Hitler [might have] felt about intimate relationships, how he felt about himself, his level of self-consciousness, and thereby goes some way to explaining why he devoted himself completely to politics, to the exclusion of any kind of private life or relationships.

Hitler is obviously not the only political figure to have foregone intimate relationships or sexual relationships or romantic relationships. But if we compare him to all the other leading Nazi figures, he is the outlier. All the other senior Nazis had wives, had children, often had extramarital affairs. So Hitler is unique in that respect and historians have puzzled over why this was for a long time. And I think this finding of Kallmann syndrome is really very significant and striking because it adds that final piece of the puzzle in explaining why Hitler basically didn’t have a private life.

So as a historian, you do think there are real findings here that help explain Hitler’s personality and even his actions?

AJK: Absolutely. Now they don’t explain all of his actions by any stretch. We talked earlier about environmental and social factors, the context of the times in which Hitler lived and his childhood experiences. All of those factors are equally, if not more, important than any genetic findings. However, these genetic findings contribute to our understanding of Hitler and why he behaved in certain ways.

Hitler did have a relationship with Eva Braun. Do the findings shed any new light on that particular relationship?

AJK: Not specifically about that relationship as such, but it tallies with what we know about that relationship. Everything we know suggests that Hitler and Eva Braun were companions as much as anything else. We have numerous eyewitness statements from people who were close to them, from people who spent a lot of time with them. Hitler’s caretaker of eight years at the Berghof, his mountain retreat, Herbert Döhring, said there was never any evidence that Hitler and Eva Braun had sex. Christa Schroeder was one of Hitler’s secretaries for 12 years. She said exactly the same. Heinrich Hoffmann, who was the photographer who introduced Hitler and Eva Braun in the first place, said their relationship was always platonic.

We also know they didn’t share a bedroom, either at the Berghof, in Hitler’s bunker in the final weeks of the war, or in Hitler’s suite of rooms at the Reich Chancellery in Berlin. They always had separate rooms, so everything points to this having been a platonic relationship and not a sexual relationship.

One of the experts featured in the documentary is Professor Simon Baron-Cohen, who’s director of the Autism Research Centre at Cambridge University. He says: “The experience of neglect and abuse” – which you have talked about, Alex, in Hitler’s childhood – “is much more relevant to understanding why someone grows up with hate and anger rather than the genetics – the two interplay.” I wondered if either of you had anything you’d like to add to that?

TK: As a geneticist, I’m the first person to say that genetics is just a part of the puzzle of who somebody is. This is where, again, it’s marrying genetics up with the history when we talk about what appears to be a genetic predisposition. We’ve got to set that really in the context of who was this individual? How did he grow up? What was the time that he was growing up in? The genetics is only going to give you a very small part of who somebody is and goes on to become.

AJK: Simon Baron-Cohen is obviously in a much better position to comment on the relative importance or impact of genetics versus upbringing or childhood. However, I would be inclined overall to agree with him that environmental and social factors, particularly neglect and abuse during childhood, have a huge impact on the adult that a person becomes. And therefore, as I said earlier, these are at least as important as genetic factors – and I would be inclined to say more important. As we’ve been stressing, the genetics is only a part of the jigsaw puzzle, and doesn’t explain and cannot explain everything.

We are talking in the middle of a week where you’ve been at the centre of a media storm. Has the backlash in some quarters been along the lines of what you expected or has anything here come as a surprise?

TK: I don’t want to speak for Alex, but we knew it was going to be controversial. For me, the most important thing to do is to say: “This is what the DNA can say, this is what the DNA cannot say.” We knew that some parts of the media were not going to listen to that, but all we can do as scientists is just keep the guardrails in about what we can and cannot say from somebody’s DNA. Again, it’s also placing all of this within the historical context.

AJK: I think we did anticipate this would be big. This is a major project. It’s a world-first analysis of Hitler’s DNA, right? We all knew it would be controversial because of who this is. That’s perfectly understandable. I think we all also expected some dissenting voices. I personally have been a little surprised at just how huge it’s been and how global the response has been in the media. I wasn’t entirely expecting this magnitude of response.

TK: I think it goes back to what Alex was saying about a responsibility in the media to report accurately. And while we knew that some people were not going to do this, in some ways the magnitude of how it’s been portrayed was something that I don’t think any of us were quite expecting.

What do you hope is the next stage for our understanding about Hitler and the period of history in which he was part?

TK: From a geneticist’s point of view, we have done this analysis. I keep coming back to the guardrails about what DNA can and cannot say, and context. It’s another layer of information that historians such as Alex can draw on in terms of how they understand Hitler.

AJK: I’m still trying to digest the reactions to this step in our attempts to understand Hitler. I think I say somewhere in the documentary that this will change the way we think about Hitler in the future and that we’ll be talking about it for a long time. I stand by that.

I do think that it has added very significant new information and added a new layer of understanding. I don’t know if this is realistic, but I would actually hope that maybe in the future we can treat Hitler a little bit less like a mythical figure or a monster, although he was certainly guilty of monstrous acts, and instead try to understand how a human being can get to the point where they do this kind of thing.

I’ve always been a little bit concerned when people dismiss Hitler and the Nazis as monsters, because if we dismiss somebody as a monster then we’re not obliged to explain them or understand how they could commit the acts they committed. But the scary fact of the matter is that Hitler was a human being and all of those hundreds of thousands of Nazi perpetrators who did monstrous, horrific things were human beings. So sadly, we need to understand how this was possible.

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