Ok, I gotta ask THE QUESTION. does Kusuri's dad knows he is dating his own mother?
I mean, Rentarou and Yaku zinged and started dating at the dad's house, though I'm not sure if he was in the room for either. And while Yaku might play the relationship close to her chest — her whole "women have secrets" bit — I'm almost positive that Kusuri has blabbed to her parents about how much fun it is that she's sharing a boyfriend with her faaaavorite granny. So yeah, I can't imagine he
doesn't know.
That said, I imagine he feels more justified in objecting to the relationships of his (often young) daughter than those of his mom, and he's grudgingly accepting Rentarou anyway.