When it was time to choose the relationships, I considered for a while to use some sort of family. I decided against it. I am rather interested in Incest, but, it HAS to make sense.
I took a look before playing and there was some debate about what would be the best choice and what the pitfalls were. That's why, instead of trying to go for a pseudo incestuous relationship, I chose to go with Counselor Judy and Friends with Haley and Mia. This setup worked flawlessly. The dialogues make sense. They address each other correctly. And so on.
From my perspective, it is WAY better to have the dialogues make sense, the whole thing isn't forced, than it is to have a minimal thrill of a non-existing Incest forced upon the story. If it is to have Incest, then it has to be there explicitly and purposefully. This "maybe" thing doesn't cut it and unless the Dev commits fully to make it work it will always create Plot Holes and Weirdness sooner or later.
Before typing this, I went back and tried Aunt Judy and Cousins... and it wasn't pleasant. At all.
TL/DR: Tried the fake incest, didn't work for me.
Peace