Given the fact it’s a prequel, Boo’s age and the likely high number of years it is possible Boo’s biological parents have not even met yet let alone preformed pro-creative actions resulting in herself.
See this is another reason why I wanted a sequel. Boo’s parents (or gaurdians, whatever works).
I am incredibly intrigued and curious as to what happened and the possible reprecussions of her being a full 24 hours were if there were any- like them being there. Clearly it seems they didn’t lose her to social services after a year but that’s not to say it didn’t have an effect on them. After putting their daughter to bed she just disappeared with no sign of forced entry. That’s the stuff of parental nightmares there. The fact she returns would obviously be a relief but ultimately freak them out. Boo it seems is not abused either nor neglected.
And even the worst babysitter in the world would notice she was gone 24 hours nor would I think good parents leave such babysitters for a very long period (say overnight). Of course if it was an incredibly selfish person they might put off reporting it through fear of getting into trouble, though they’d also be an idiot sine there was no way to plan for such a thing to happen as monsters aren’t real to them. (At the very least a person would instigate a wide search with the help of neighbours/locals if anything if they thought of anyone other than themselves).