Ian was born in Los Angeles, he never knew his mother and his father died from a drug overdose when he was five. His grandfather who lived in Vancouver heard about this and flew down to try and claim rights to take care of him. Eventually it worked out and Ian flew up to Vancouver to live with his grandfather and uncles.
While Ian's grandfather was in LA he met with business partners to discuss new ideas of smuggling drugs across the Canadian/US border. The idea was simple, the drugs get made in Mexico and then smuggled across the borders and distributed into the USA and Canada. But the execution was less simple, they needed to be creative with figuring out way to make sure they didn't get caught.
They weren't creative enough, after a few years it all went to shit, a lot of the partners they dealt with were either arrested or dead but Ian managed to get out of it without any charges for breaking laws or without bullets in him. Seeking a change in life and claiming to be reformed he managed to join the Canadian Armed Forces, after a few years of training and other minor deployments he was deployed to Chernarus with a small team to assist with other nations and worked closely with the 501st. Due to complications he was stuck and most of his team didn't make it, and the people he was stuck with were the 501st. Seeing how he was there for a reason, he has no reason not to stick with the mission and assist the 501st with what was happening, becoming an official member as the world fell apart around them.