Olssøn was born in Horten in Vestfold, Norway. He was the son of Edvard Olssøn  (1820–1867) and Leonore Rebecca Bredal (1820–1910).
Olssøn's birthplace was Horten, located in Vestfold, Norway. He was the son of Edvard Olssøn (1820-1867) and Leonore Rebecca Bredal (1820-1910).