His dad designing an AI that is corrected directly to your brain is an easy reason
Good point.
I'm thinking dad Ryder might turn out to be...a renegade character, Not a "bad guy" but he created something that was outlawed by the Citadel council and I think that will play a role in the story, and perhaps explain the real reason he fled the galaxy. He's described as distant when the game begins, and the AI he created will supposedly fill in the mystery of your parents, whatever mystery that is.