TV Review: Hitler's DNA – Blueprint of a dictator

What does a documentary about Hitler's genome tell us about the future of baby-making?

The Channel 4 documentary 'Hitler's DNA: Blueprint of a Dictator' has two flaws: it comically contradicts itself at times and inadvertently proves points it never intended to make at others. Wearing my geneticist hat, I've flagged three instances of this involuntary irony. Not to ridicule a sensationalist show, but as an opportunity to discuss the technology at its core, a tool that may change human reproduction: polygenic scores (PGSs).

The documentary begins with a team of scientists who acquired, authenticated and sequenced a sample of Hitler's blood to gain a window into his personality. This was my favourite part – 'casually' not involving PGSs – as it expertly intertwined historical documentation and forensic science in a captivating detective story. Indeed, the show first established the sample's origin: a patch of bloodstained fabric that an American soldier cut out from the sofa where Hitler shot himself. Then, it makes a compelling case for the blood being Hitler's by comparing the Y-chromosome sequence from the bloodstain with the Y-chromosome of his verified living male relatives, conclusively linking the sample to the Hitler paternal line.

With the authenticity of the DNA confirmed, historically and scientifically, the show can finally ask its big (and naïve) question: did the Führer's genome prime him to commit the atrocities he is infamous for? The answer comes from calculating Hitler's PGSs. These measure the strength of association between a certain combination of gene variants (alleles) and a specific trait or condition, as most human characteristics are associated with hundreds to thousands of genes. Early on, the documentary points to Hitler's high PGS for behavioural traits such as schizophrenia and bipolar disorder. This discovery seems to imply that yes, Hitler's genetic makeup was a driver of his infamous crimes against humanity.

While the documentary uses these metrics as a lens to examine the past, some people claim that PGS will shape our reproductive future – as reflected in recent advertisements on the New York subway encouraging would-be parents to select embryos on the basis of predicted traits, such as height or intelligence (see BioNews 1302 and 1318). This genomic screening test, known as PGT-P (preimplantation genetic testing involving polygenic scores), is offered in the USA, but screening embryos for non-medical traits is not allowed by UK law (see BioNews 1130, 1137 and 1232). However, recently a UK fertility clinic has reported that patients are requesting genetic data obtained from permitted embryo tests – such as preimplantation genetic testing for monogenic conditions (PGT-M), structural chromosome rearrangements (PGT-SR) or aneuploidy (PGT-A) – sending this data to US firms for analysis and then requesting specific embryos are transferred (see BioNews 1319).

Now that we share a common background, I can walk you through three ironies that I spotted in the programme. This analysis will provide us a chance to cast a more critical light on the power of PGSs.

I watched the programme with my non-geneticist, history-buff fiancée, who became increasingly irritated. Early on, the show claims that its genomic-centric analysis will change our view of the Nazi dictator. Then, it lists various mental traits with high PGS and presents anecdotes from Hitler's life to show that history 'confirms' the genetics. No trace of the promised new outlook: the documentary used the Führer's actions to back up observations on his genetic makeup, and not the genome as a blueprint for the behaviour. In a deeper irony, this storytelling aligns better with how biology works: our genome is not a blueprint but a toolkit that enables us to adapt to the world around us.

The cardinal sin was the frequent misuse of the concept of PGS, an ironic confusion for a documentary with genomics at its core. The show presents the PGS as a blueprint, a diagnosis, for someone's behaviour. This is not what they are. PGSs are (often weak) predictions: probabilities across a group. The logic of the show is equivalent to finding an above-average PGS for height in a tall adult and treating that score as the only reason for their stature. In reality, an elevated PGS for height in a child only indicates they may grow taller than average.

The final irony is subtler, and yet harsher. PGSs are heavily biased towards populations of European-descent, as most datasets used to set up these indexes are generated from studies on people of this origin. As a consequence, PGSs are even less accurate for non-European descendants. It is ironically fitting that an ethnically-skewed tool is used to analyse the genome of history's most notorious racist.

A bonus irony is that the strongest (albeit still speculative) insight into Hitler's health and personality comes from a mutation in a single gene and not from the aggregation of thousands of gene variants (the methodology of PGSs). This single mutation, in the PROKR2 gene, may have caused Hitler to suffer from Kallmann syndrome, a condition that delays or blocks sexual maturation. Interestingly, this genetic diagnosis aligns with and potentially explains long-standing, but unverified, historical rumours concerning Hitler's sexual development and physical abnormalities.

In the end, 'Hitler's DNA: Blueprint of a dictator' is a frustratingly oversimplified version of history and science, one where a man's crimes are driven by his genome. This caters to our craving for stories with a logic and a meaning, and it must make for higher ratings.

Likewise, private fertility companies may present an overly optimistic vision of these same concepts, catering to parents' hunger to grant their children 'the best story', one where they have peak intelligence and athleticism. This is why it is so crucial to discuss what PGS can – and, more importantly, cannot – do.