I thought about this for about 5 minutes. It's a question that's difficult to answer. I guess it would depend on a few things. Although It's hard to even imagine going with the man. I don't have any sisters, so that might be making my decision more difficult.
Doesn't the Bible say somewhere that it is OK to do your sister, but you must be stoned if you lay with a man.
BTW, I don't know why the example of a sister or man is being used. The woman was having sex with her FATHER.
Well, definitely sister if it's kind of the like the case with the other story where you didn't grow up with her and you don't know that it's your sister. Now, if the question is my actual sister that I grew up with? That's a fcking impossible question to answer.
During sex he couldn't tell a difference. Really not the end of the world. The fact that she hid it is wrong, but amazing that you can say you love someone, be attracted to them, be fine with the sex, and then be repulsed by the person because they used to be a different gender. I'd still divorce her, but geez.