Well, half-brothers and half-sisters are not related at all, so it can't be considered something bad or immoral. It's no surprise that an adult guy and girl, with no regular sexual partners and almost daily being around each other, suddenly felt attracted on a sexual level to each other. Considering that the girl liked it (the guy then no question), I think they will continue to practice this kind of thing from time to time.
The old professor is still so chipper! About his age except that the skin indicates, and so the device works and functions as it should. This was not particularly pleasant for the student, but what can you do, if she did not want to learn. She should have thought about it earlier, or else she had to catch up with everyone else by urgent intake of proteins and proteins from smarter people. It's okay, a semester or two and she'll be up to speed.