Zinnow, on the other hand, came from a working-class background. His father was a stone mason. Both of his parents died during a cholera pandemic so, following a stay in an orphanage, he was adopted and raised by an aunt. After finishing school, he was apprenticed as a bricklayer and attended a trade school. In 1866, he found employment as a draftsman in the elder Stammann's office. In 1873, during the building boom that followed the Proclamation of the German Empire, Hugo took him on as a partner. Two years later, he married Bertha Philippine Beit (1851–1907), the sister of Alfred and Otto Beit.