I absolutely love the fact that Bobby's favorite memory is not of a spectacular creature kill, or of the boys surviving a particularly nasty case, or anything hunting related. His favorite memory is the boys just being boys, being normal brothers.
John did what he could, but Bobby. Bobby did more than he could. He went above and beyond for these boys. I do respect John and what he had to do, but I believe Bobby to be they boys' real dad, and John to be their Father.