Ferdinand Heiden was the child of Christoph Ludwig Friedrich "Ludwig" Heiden and his first wife who was German. He born November 17, 1851 and baptism November 30, 1851.

Ludwig, who had moved from Germany to Sweden was a younger brother of August Heiden's mother, Maria Heiden. Therefore, he was an uncle to August and his half-sister, Fredericka (Heiden) Schmidt.

On January 27, 1883, Ludwig sent a letter to his nephew, August Heiden in America containing this information. According to the letter, "Ferdinand is a Catholic priest in Copenhagen."  Ferdinand would have been August's first cousin.