I can only let you know that I've met mum's who've had GD with one pregnancy and not others. I'm not sure if there really is a genetic link between GD and T1 or T2 but I suppose the people making up all those statistics might have some idea, or not.
One clue to whether you may or may not have GD with a previous pregnancy would be based on the weight of the newborn. GD untreated tends to cause large babies. Even though you might think 9.6 isn't that high it is considered out of range for pregnancy. You might be able to diet control the diabetes and avoid meds.
All the best for you and the new bub.