Kids in jeopardy are a staple of cop shows and movies (and television news sweeps programming) for a reason: They get us where we live. Despite that, I haven't seen it much in D&D, and wanted to leverage that motivation in the campaign. (It doesn't hurt that Emmerson is a family man.)
The whole bit with the Kramer twins and the young stepmother are taken from a college kiddie-lit class, where they explained the whole origin of the evil stepmother thing: So many women died during childbirth, or soon thereafter, that young stepmothers whose child stood to inherit nothing while the original wife's children lived, were not uncommon.
A parallel could be drawn between this adventure and the story of Hansel and Gretel, but as you'll see, it's mostly a tenuous link, although it does inform a little bit of what happens at the end.