[Doug]

I dont' like A at all, for the reasons you mentioned.

I don't like C, because a parent has a special responsibility towards a child as well as having a special relationship with them, and I think a parent that allows this to happen has broken a sacred trust -- who knows what would happen to the kid psychologically as time went by. Also, to be less cerebral about it, I just find it kind of icky.

I don't find B objectionable at all, and actually rather intriguing. Although there exists the same "raised as kin" aspect, you don't have the special parent-child trust thing going on. And of course, there are no genetic ramifications. It has a good mix of being socially objectionable and yet it's not fundamentally wrong (I dont' think).

I guess what it comes down to is that I could imagine personally being involved in situation B., but never, ever, ever in A. or C. That's just me, though.

Having said all that, I think you should write about whatever moves you. I have always enjoyed writing, but I could never think up the story lines that writing fiction requires, and I envy and admire those who can. You might as well go with what inspires you.