Jun 30

Jun 30 Answer's on the back of a postcard

Two postcards — Postcard sent by Renc from Vienna in 1918 and postcard sent by Arles from Rankweil in 1922. Image from Haas et al (2022)

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Genetic fingerprinting doesn’t have to be used only for big, high profile dramas like international espionage. Sometimes it can reveal the small, personal stories lived by everyday people which are no less meaningful. One such story was uncovered at the start of this year by a group of Swiss geneticists who were asked if they could help lay to rest a family secret that had hidden in the shadows for nearly 150 years…

The year is 1885, and in the recently formed Austro-Hungarian empire, a young blacksmith, Xaver, falls in love with his boss’s beautiful teenage daughter, Dina, but when her father, the boss, finds out, he is furious. After all, Dina comes from a Catholic-Jewish family, and Xaver is a gentile.

Xaver is fired from his blacksmithing job and travels to the city, finding work in a factory. But these star-crossed lovers could not be separated for long, and Dina runs away from her father in order to be with Xaver. Life is not easy in a big city for a 17-year-old Catholic-Jewish girl with no family support, but luckily Xaver’s new boss Ron, the factory owner, is also Jewish and his family takes Dina in to work as a servant for them.

To recap: we have Xaver, the plucky blacksmith who is dating Dina, the pretty servant girl who works for Ron, the factory owner. Got that? Good. And you can probably see where this story is going.

Although Ron, the factory owner is 30 years old, he takes a shining to his new servant girl. Despite the fact that Dina and Xaver are still a couple, Dina also “becomes close” to the factory owner, Ron, and nine months later gives birth to a baby boy, Renc. Renc is baptised as a Catholic, like his Catholic-Jewish mother Dina, and also given Jewish rituals, just like both Dina and Ron had when they were born.

You would have thought that this child, Renc, would cause havoc on the love triangle, but oddly enough, everyone seemed to be just fine with it. After a year and a half of working in Ron’s factory, Xaver makes a good career for himself and marries his childhood sweetheart Dina, adopting the baby Renc in the process as his stepson. Xaver and Dina have three kids, meaning baby Renc now has a younger half-brother, Arles and two other half-siblings.

Of course, any story about a Jewish family living in the Austro-Hungarian empire in the early 1900s isn’t going to stay happy for long. Through World War I, the half-brothers Renc and Arles fought on the battlefields, and miraculously both survived. However, it wasn’t long before World War II arrived and the Nazis required them both to prove their ancestry to show whether or not they were Jewish.

The younger brother, Arles was ok; his dad Xaver the blacksmith was a gentile. Renc on the other hand had a much harder time. Both his mother, Dina, and his true father, Ron the factory owner were Jewish. So he lied. He pretended that he was Xaver’s son, rather than stepson, and managed to use his family’s Catholic baptism status to avoid being outed as a Jew. His life throughout the war was burdened by this big secret, knowing that if the Nazis found out, they would likely send him to the concentration camps. Renc even kept this secret from his family, and only revealed his true parentage to his children on his deathbed.

One hundred years passed, and Renc and Arles’s grandchildren learned of their family’s great secret. But they weren’t convinced of who Renc’s dad was, so they turned to genetics, enlisting the help of Dr Cordula Haas from the University of Zurich.

The easiest way to check would be by looking at the Y chromosome, the ‘male’ chromosome passed only from father to son. If Renc and Arles had been full siblings, they would both have inherited the same Y chromosome from their father, Xaver. But if Renc’s true father was instead Ron, he would have had a different Y chromosome.

But that would be too easy! Both Arles and Renc only had daughters, so their Y chromosomes never made it into the next generation. If only the grandchildren had some of Arles’ and Renc’s DNA, they could just test that. But where were they going to find a sample of their grandparents’ DNA? Where would you look, dear listener? Why not send in your answers on the back of a postcard.

Answer’s on the back of a postcard. Of course! The family still had some of their grandparents’ postcards that had been posted around 1922, back when stamps were licked rather than self-adhesive. If Arles and Renc had licked the stamps themselves (rather than a post office worker), and the DNA from their saliva was still intact in the glue after 100 years, and somehow you could get the DNA out of the glue without damaging it, and it was possible to still sequence that DNA, well if everything went right, you could maybe compare their Y chromosomes.

To start with, Haas needed to check if the postage stamps even had saliva on them, or whether they had just been wetted on a wet pad. Luckily there are very straightforward kits for this that look just like a Covid lateral flow test, designed for forensic testing of crime scenes. And yes, the stamps contained human saliva. They were off to a good start.

Now they had to extract the DNA from the stamps. They carefully cleaned the front of the stamp, which could have been touched hundreds of times and steamed the stamp off the envelope. They then swabbed the back of the stamp to run a DNA test, looking for short tandem repeats; tiny sections of DNA code that get copy and pasted next to each other, but the number of these copies varies from person to person.

They compared the autosomes - the non sex chromosomes - from the stamps against the grandchildren. The DNA on the 4 postcards Renc wrote were indeed similar to Renc’s grandsons, so we know that Renc himself must have licked the stamps. One of the postcards Arles had written came up with female DNA in the saliva on the stamp. Presumably a maid or a postal worker had licked that stamp instead of Arles, but luckily the second postcard they had from Arles came up as a family match for his granddaughter.

We now know we have the 100 year old saliva from both Renc and Arles, and the DNA is still intact enough to compare their Y chromosomes. Were they indeed half brothers, with Renc the illegitimate child of the Jewish factory owner? Or were they full brothers, with gentile Xaver as Renc’s father?

The results were a revelation. Renc and Arles…were full brothers. Even though Dina may have slept with the factory owner Ron, her first-born child was fathered by her childhood sweetheart Xaver. Sadly, though, not even Dina knew this. Renc wrongly believed that his biological father was Jewish at a time when that information could cost him his life. He forged a lie and had to present it to Nazi scrutiny, knowing that any wrong move, any slip of the tongue, would see him sent to a concentration camp.

If only he knew. The lie he made up was the truth all along.