Gotthold Eisenstein's father was Johan Konstantin Eisenstein and his mother was Helene Pollack. The family was Jewish but before Gotthold, who was their first child, was born they had converted from Judaism to become Protestants. Their family were not well off, for Johan Eisenstein, after serving in the Prussian army for eight years, found it hard to adjust to a steady job in civilian life. Despite trying a variety of jobs he did not find a successful occupation for most of his life, although towards the end of his life things did go right for him.
Eisenstein suffered all his life from bad health but at least he survived childhood which none of his five brothers and sisters succeeded in doing. All of them died of meningitis, and Gotthold himself also contracted the disease but he survived it. This disease and the many others which he suffered from as a child certainly had a psychological as well as a physical effect on him and he was a hypochondriac all his life. His mother, Helene Eisenstein, had a major role in her son's early education.
He wrote an autobiography when about two years old and in it he describes the way that his mother taught him the alphabet when he was a child, associating objects with each letter to suggest their shape, like a door for O and a key for K. He also describes his early talent for mathematics in these autobiographical writings