As a mutant ~6x over I can say with certainty that it’s a terrible idea to normalise incest.
All Ashkenazi Jews are genetically fifth cousins at the very least, and married their cousins for millennia. Now I’m autistic, my connective tissue barely works and I have mood disorders.
I know it’s fiction, I’m just reminding y’all that there is a good reason incest is considered not ok.