Christian concepts of sin + punishment are dumb and stupid and I'm sick of pretending otherwise.

The fact that they live actually makes it all the more horrifying because they have to live in a family that likely despises and hates them for their warped and strange appearance, and in a world full of people who likely will treat them as subhuman for the rest of their lives. Kids dying is dark but honestly way less dark then body horror.

I don't really think anyone should suffer for arrogance or vanity. It's not really a personality flaw that manifests as much more then 'mildly annoying' unless they have power or wealth, in which case there tends to be lots of other issues with that in general.