So putting aside the "why" of a wizard/hag coupling (maybe the hag was in disguise? I've only seen it said that hags can't hide themselves/their true form from muggles, and then besides that it said somewhere they have shapeshifting capabilities)...
Anyway! In that case, what would a human girl of hag decadency categorize as? A regular human or a half-breed? A quarter-hag? Considering how far down the line from the original hag you have to go to get the possibility of a human daughter, I'm not sure how you would label that; would anyone outside the family know at that point? (Maybe they would, as I imagine doing the deed with a hag would be a big hit to your and your family's reputation...)
Other random questions regarding this:
- Would hag descendants have a possible proclivity towards the dark arts?
- Could, theoretically, the son of a hag go on to marry a muggle (maybe a desperate attempt to escape judgement by the Wizarding World...) and still have hag daughters? I'd assume yes, but just a thought, especially given how the Ministry has their "keep everything magical secret" motto going on even in VE.
- If you made such a character (a child of a hag/human or a descendant of such a couple), would they fall under the non-human template or the human one?
- NEW(/edit, ty for this one Kelly <3): would a play-by for a half/part-hag (or maybe even some further down the line) by allowed hair of an unnatural color as a physical oddity? I believe I saw that hags can have anywhere from black to green hair...