There is no information about what happened to Albert Einstein's first daughter.
In 1896, Einstein renounced his German citizenship and enrolled at the Swiss Federal Polytechnic School in Zurich. There, he began a passionate love affair with Mileva Maric, a fellow physicist-in-training originally from Serbia. The couple later married and had two sons after graduating, but a year before they tied the knot, Maric gave birth to an illegitimate daughter named Lieserl.
Einstein never spoke about the child to his family, and biographers weren’t even aware of her existence until examining his private papers in the late-1980s. Her fate remains a mystery to this day. Some scholars think Lieserl died from scarlet fever in 1903, while others believe she survived the sickness and was given up for adoption in Maric’s native Serbia.