Incest iss s** between close relatives, such as a brother, sister, or parent. This typically includes any kind of sexual activity between people in consanguinity (blood relations), and sometimes those related by lineage.
@Bread I know what incest means, ty for explaining what I already know. Besides saying "it does not matter whether or not they are blood related", I did not say it was incest now, did I? My point was that it's weird either way. Reynold didn't see her as a sister either, yet he never developed romantic feelings for her. And Derrick did not have those feelings when they were kids, they only appeared after Penelope changed. Childhood psychology would only be relevant if he had those feelings as a kid, but the novel doesn’t show or mention that + no one has said that it's been shown -- if I am not wrong. Him not treating her as a sister doesn't mean that it's reasonable to develop romantic feelings later. And considering he's an adult and no longer a child, he should know that it's wrong and stupid. So your argument doesn't really work. And I'm sure I know about psychology more than you, considering I focus on that area, so ya ^_^ Feel free to keep arguing but you're wrong about basically half of what you've said. Have a good day ❤️