 He had a sister, Charlotte, and two brothers, Gustav Heine von Geldern (later Baron Heine-Geldern and publisher of the Viennese newspaper "") and Maximilian, who became a physician in Saint Petersburg.Heine was also a third cousin once removed of philosopher and economist Karl Marx, also born to a German Jewish family in the Rhineland, with whom he became a frequent correspondent in later life.Düsseldorf was then a small town with a population of around 16,000.