Please assure your son that he has asked a very important question. I’m glad he’s thinking about heaven. The good news is that in heaven we will all have glorified bodies. That means we will be made new and complete. You will still be you and your son will still be your son because individual personality survives death.

But all the limitations of this life will finally be removed. Will your son remember his disability? I think the answer is yes, and he will be glorify the Lord who graciously enabled him to trust Christ in this life. In that day all that hinders us will finally be removed. We will be raised immortal and incorruptible. That means all the imperfections of this life will be gone forever. You can read about this in 1 Corinthians 15:51-57.

See From Acorns to Oak Trees.