James was born out of wedlock to Thomas Fairbairn and Elizabeth Simpson, but the parents were later married in 1856 before emigrating to New Zealand with their growing family. They settled on the Otago peninsula just outside of the city of Dunedin, in the province of Otago.
It may be possible to confirm family relationships with James by comparing test results with other
carriers of his Y-chromosome or his mother's mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree: