Is dirks dad is technically Dave and Roxton mother is rose, doesn't that make roxy and dirk siblings and any romantic feelings roxy had toward him incest? Sorry but this question has been annoying me since forever. Thanks.

No, you’ve got it mixed up. Dirk and Roxy are not related at all. Dave and Rose are their genetic offspring so Dave and Rose are siblings. Dirk and Roxy are genetic clones of themselves and have no parents.