Olssøn was born in Horten in Vestfold, Norway. He was the son of Edvard Olssøn  (1820–1867) and Leonore Rebecca Bredal (1820–1910).
The provided text states that Olssøn's birthplace was Horten, Norway, and he was the son of Edvard Olssøn and Leonore Rebecca Bredal.