Born aboard the spaceship of his parents Mark is basically living his entire life out in space. Raised aboard his parents ship he served aboard it, until they were killed when pirates destroyed their ship after his father didn't want to abandon an especially expensive load to them. The family simply would not have been able to pay bear the loss.
Mark was about 25 of age at that time and not having learned to do anything but trading in space the young man went on this career. Mostly going the trading route, only occasionally hiring himself out for combat missions. He served both inside the Federation and Empires Navies. Mostly as a way to open himself new paths in the respective nations territories.