I think they probably knew deep inside, and that's what made it extra-spicy for Luke. It's like that episode of Angelika Kallwass, where a brother and a sister who were raised separately and then fell in love now knowing that they're siblings. At least that's what we're made to think, but then it turns out the guy knew all along and that's why he even started having a relationship with her, and then she's like: "Yeah, I realized that something's weird, but it felt good.", and in the end they're told by Kallwass to stop dating because that's not allowed and they're like: "Alright, I guess. Let's break up." - and that's where the episode ends. But in my brain I know that they kept having sex with each other, and she probably got pregnant shortly after. And the baby was fine too, just a bit slow and with an awkwardly large head, but otherwise it's fine, so it's a happy end.
Pretty kinky.