heres a pretty good interview with Giancarlo Esposito on what you guys were talking about Gus' character. it seems like Vince Gilligan wants to leave it open to the viewer, to decide his history. but who knows they may show some flashbacks to the past next season that sorts it all out.
"Which they definitely did, especially, as we discussed, in the "Hermanos" episode. It was so satisfying for viewers to get a glimpse at what motivates Gus … did you feel that way, too, when you read the script?"
With this (episode), the triumph was that they asked me for some family pictures. I brought in pictures of my four daughters and put them all on the wall. (Viewers) never really saw them, but just in case one day they did and wanted to reflect back to that scene, they could see my family, which meant (Gus) could have a wife. I could have this whole, other … I could be living like Gus does in plain sight, but have the trimmings of the whole family. We haven't seen that. I don't know if that will happen. But, yes, for people to see the background of a character that you create and understand … because a lot of our villains that we experience, in many ways they're one note. I certainly didn't want to have Gus be that.