Like Smallville, The Graysons will take elements of the character from DC Comics continuity, and put its own spin on it. In the original origin of Robin, there was virtually no backstory given, save that his parents died as a result of a gangster’s extortion scheme at the Haly Circus, where the Flying Graysons were performing. Some backstory has been added in since that story in 1940’s Detective Comics #38, but never with the scope that The Graysons is aiming at.
From Variety:
In the one-hour "Graysons," which will be set in modern times, young DJ will face challenges involving first loves, young rivals and his family as he grows up. Souders and Peterson have come up with an original take on the character.