Just a year after she was born in 1902, Albert Einstein’s daughter Lieserl Einstein suddenly vanished from the historical record — and until 1986, no one even knew she existed.

Public DomainAlbert Einstein and Mileva Marić 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 Marić, 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 Marić married.

But then, Lieserl Einstein disappeared. And she remained hidden until well after both Marić’s and Einstein’s deaths in 1948 and 1955. It wasn’t until discovering decades-old personal letters between the two in 1986 that Einstein’s biographers even learned that she existed at all.

So, what happened to Lieserl Einstein, Albert Einstein’s only daughter?

Albert Einstein with his step-daughter Margot at the opening of the Jewish Pavillion at the World’s Fair in Flushing Meadows in Queens.

The Mystery Of Albert Einstein’s Forgotten Child

Lieserl Einstein was born on Jan. 27, 1902, in the city of Újvidék 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 Einstein’s daughter.

Her disappearance was so complete that historians never learned about Einstein’s 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 Marić, c. 1905.

On Feb. 4, 1902, Albert Einstein wrote to Mileva Marić, “I was scared out of my wits when I got your father’s letter because I had already suspected some trouble.”

Mileva had just given birth to Einstein’s first child, a daughter they referred to as Lieserl. At the time, Einstein lived in Switzerland, and Marić 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 physicist’s questions went on and on. Finally, he said, “I love her so much and I don’t even know her yet!”

Albert asked Mileva, “Couldn’t 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 she’ll 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 Einstein

When 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 Marić were unmarried when they had Lieserl. The pregnancy disrupted Mileva’s plans. She had been the only woman in Einstein’s class at Zurich Polytechnic. But after learning of her pregnancy, Mileva withdrew from the program.

Albert’s family never approved of Mileva. “By the time you’re 30, she’ll already be an old hag,” Einstein’s mother warned of the woman who was just three years older than him.

Despite his family’s misgivings, Albert married Mileva. But only after leaving Lieserl behind in Serbia, where Mileva’s 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 Marić and Albert Einstein in 1912, two years before they separated.

The last reference to Lieserl in Einstein’s letters comes in September 1903. “I’m very sorry about what has befallen Lieserl,” Albert wrote to Mileva. “It’s so easy to have lasting effects from scarlet fever.”

Lieserl had apparently come down with scarlet fever around 21 months old. But Einstein’s letter implies she survived. “If only this will pass,” he wrote. “As what is the child registered? We must take precautions that problems don’t 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 Einstein’s 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 Marić 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 Marić and her two sons, Hans Albert and Eduard.

It’s possible that Albert, so eager for a photograph of his daughter, never met Lieserl Einstein. He certainly never mentioned her in writing after 1903.

It’s also possible that Albert hid Lieserl from his family. However, a few weeks after Lieserl’s birth, Einstein’s mother wrote, “This Miss Marić 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.”

“There’s a real attempt to keep Einstein as the icon of humanitarianism and goodness, and he wasn’t 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 Marić and his sons in 1914.

In 1904, Mileva realized she was pregnant again. She waited to tell Albert, afraid of his reaction. “I’m not the least bit angry that poor Dollie is hatching a new chick,” the physicist told his wife. “In fact, I’m happy about it and had already given some thought to whether I shouldn’t 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 Einstein’s forgotten son.