It's thinly veiled incest, mainly because certain sites and location won't allow them to post actual incest games. Personally I try to ignore it and pretend they're actually roommates or stepsiblings, because I don't like incest storylines, but I had at least one other game where it was so prevalent it became humorous with sections about "roommates and half roommates"(Sisters) and "my old landlady"(Mom) and I think they named cousins "neighbors". I looked it up and there was actually a patch/mod to put the incest back in, which I considered just because the original dialog was so weird about forbidden roommate romance. That one I stopped playing when one of the "roommates" basically said when you give me a daughter, you should also "romance" her when she grows up, which was about 3 steps too far for me.