Public DomainAlbert Einstein and Mileva Mari with their first son, Hans, in 1904, two years after Lieserl Einstein was born.Albert Einstein was one of the greatest physicists in history. But for years, parts of his private life remained hidden including the fact that he had a daughter, Lieserl Einstein. Why was Lieserl a secret? Because she was born out of wedlock. In 1901, Mileva Mari, a physics and mathematics student with Einstein at the Zurich Polytechnic, left the school and returned home to Serbia, giving birth to a daughter the following year. In 1903, Einstein and Mari married.But then, Lieserl Einstein disappeared. And she remained hidden until well after both Maris and Einsteins deaths in 1948 and 1955. It wasnt until discovering decades-old personal letters between the two in 1986 that Einsteins biographers even learned that she existed at all. So, what happened to Lieserl Einstein, Albert Einsteins only daughter?Albert Einsteins Forgotten ChildLieserl Einstein was born on January 27, 1902, in the city of jvidk in what was then the Kingdom of Hungary in Austria-Hungary and is today part of Serbia. And that is just about all researchers know for sure about the life of Albert Einsteins daughter. Her disappearance was so complete that historians never learned about Einsteins daughter until 1986. That year, early letters between Albert and Mileva surfaced. Suddenly, scholars discovered references to a daughter called Lieserl. Ann Ronan Pictures/Print Collector/Getty ImagesAlbert Einstein with his first wife Mileva Mari, c. 1905. On Feb. 4, 1902, Albert Einstein wrote to Mileva Mari, I was scared out of my wits when I got your fathers letter because I had already suspected some trouble.Mileva had just given birth to Einsteins first child, a daughter they referred to as Lieserl. At the time, Einstein lived in Switzerland, and Mari had returned to her hometown in Serbia.Is she healthy and does she already cry properly? Einstein wanted to know. What kind of little eyes does she have? Whom of us two does she resemble more?The physicists questions went on and on. Finally, he said, I love her so much and I dont even know her yet!Albert asked Mileva, Couldnt she be photographed once you are totally healthy again? He begged his lover to make a drawing of his daughter and send it to him.She certainly can cry already, but to laugh shell learn much later, Einstein mused. Therein lies a profound truth.But when Mileva joined Albert in Bern, Switzerland, to be married in January 1903, she did not bring Lieserl. The child seemingly vanished from all historical records. Lieserl Einstein became a ghost. In fact, not a single letter dated after 1903 contained the name Lieserl. Searching For Lieserl EinsteinWhen scholars learned that Albert Einstein had a daughter named Lieserl Einstein, the search for information about her began. But historians could not find a birth certificate for Lieserl Einstein. Not a single medical record remained. They could not even find a death certificate referencing the child. Even the name Lieserl was likely not her real name. Albert and Mileva referred variously in their letters to a Lieserl and a Hanserl, generic gendered German diminutive names, when referring to their desires of having a girl or a boy somewhat similar for hoping for a Sally or a Billy.Left with a mystery, historians tried to piece together clues about what happened to her.ETH LibraryMileva and Albert with their first son, Hans.Albert Einstein and Mileva Mari were unmarried when they had Lieserl. The pregnancy disrupted Milevas plans. She had been the only woman in Einsteins class at Zurich Polytechnic. But after learning of her pregnancy, Mileva withdrew from the program.Alberts family never approved of Mileva. By the time youre 30, shell already be an old hag, Einsteins mother warned of the woman who was just three years older than him. Despite his familys misgivings, Albert married Mileva. But only after leaving Lieserl behind in Serbia, where Milevas family cared for her.Einstein had a motive to hide his illegitimate daughter. Working in a Swiss patent office, an out-of-wedlock child could halt his career before it began.Universal History Archive/Universal Images Group via Getty ImagesMileva Mari and Albert Einstein in 1912, two years before they separated.The last reference to Lieserl in Einsteins letters comes in September 1903. Im very sorry about what has befallen Lieserl, Albert wrote to Mileva. Its so easy to have lasting effects from scarlet fever.Lieserl had apparently come down with scarlet fever around 21 months old. But Einsteins letter implies she survived. If only this will pass, he wrote. As what is the child registered? We must take precautions that problems dont arise for her later.The scant clues left scholars with two theories: either Lieserl died as a child or the Einsteins gave her up for adoption. What Happened To Lieserl Einstein?In 1999, author Michele Zackheim published Einsteins Daughter: The Search for Lieserl. After years spent searching for clues and interviewing Serbians about family trees, Zackheim developed a theory.According to Zackheim, Lieserl had been born with unknown developmental disabilities. Mileva Mari left Lieserl behind with her family when she traveled to Bern to marry Albert. Then, some months before her second birthday, Lieserl died.Hebrew University of JerusalemMileva Mari and her two sons, Hans Albert and Eduard.Its possible that Albert, so eager for a photograph of his daughter, never met Lieserl Einstein. He certainly never mentioned her in writing after 1903. Its also possible that Albert hid Lieserl from his family. However, a few weeks after Lieserls birth, Einsteins mother wrote, This Miss Mari is causing me the bitterest hours of my life. If it were in my power, I would make every possible effort to banish her from our horizon, I really dislike her.Theres a real attempt to keep Einstein as the icon of humanitarianism and goodness, and he wasnt good, Zackheim argues. He was an enormously talented creative genius and he was a dreadful father and a dreadful person and not kind to his children at all.Ferdinand Schmutzer/Austrian National LibraryAlbert Einstein left Mileva Mari and his sons in 1914.In 1904, Mileva realized she was pregnant again. She waited to tell Albert, afraid of his reaction. Im not the least bit angry that poor Dollie is hatching a new chick, the physicist told his wife. In fact, Im happy about it and had already given some thought to whether I shouldnt see to it that you get a new Lieserl.By then, mere months after Lieserl Einstein disappeared from historical records, Albert already had his mind on a new Lieserl.What happened to Lieserl Einstein? Whether she died as a child or her parents gave her up for adoption, Lieserl vanished from history.Albert Einstein had at least two children after Liesel. Learn more about his son Hans Albert Einstein, a renowned mechanical engineer who taught at Berkeley. Then read the depressing story of Eduard Einstein, Albert Einsteins forgotten son.The post Inside The Mystery Of Lieserl Einstein, The Secret Daughter Of Albert Einstein appeared first on All That's Interesting.