Giovanni Semeria was born during the aftermath of the 1866 Italian War of Independence. In accordance with his late father's wishes, he was born in Colle which at that time was an autonomous municipality, but which has subsequently been renamed as Coldirodi and in 1925 subsumed into San Remo, a sprawling coastal municipality along the coast between Genoa and Nice. His father, also called Giovanni, died when an outbreak of Cholera gripped the regiment in which he was serving during the course of the war. His widowed mother settled near Turin and took as her second husband Pietro Grosso. The fact that he was an orphan conditioned Semera's entire life.