Ross was born January 13, 1885, in Naughton, Ontario. His father, Thomas Barnston Ross, was of Scottish descent and originally from Chicoutimi, Quebec, while his mother was Marguerite (Margaret) McLeod. Ross's parents initially lived in Lake St. John, Quebec (now Lac Saint-Jean), where Thomas worked for the Hudson's Bay Company (HBC). The family had ten children: nine sons and one daughter. Around 1876 Thomas was transferred to a trading post in Northern Ontario close to the Whitefish Lake. Living in a remote outpost, the family would trek each way twice a year for supplies.