A Christmas Carol presents family life as the most normal and healthiest experience that all humans should aspire to. How Victorian! The inspirational characters are members of large families or family groupings—Bob Cratchit, Fezziwig, the miner, and Scrooge's ex-fiancée. But even the family-less folks strive to connect in family-like groupings. In the end, it is not enough that Scrooge simply be rehabilitated as a person—he also has to be re-incorporated into family life as Fred's uncle and father numero dos to Tiny Tim.
You know what? The ghosts are kind of a family unit, too.
The most crucial moment of Scrooge's transformation is when he tears up at the thought that his ex-fiancée's children could also have been his own. We mean, he cries for crying out loud. Pardon the pun.