Luke and Leia would have turned out as two complete weirdos by the time of the OT. Growing up totally isolated on a swamp planet in the middle of nowhere, the only other sentient being they have ever had any kind of contact with being Yoda. We saw how Yoda had lost it a bit in TESB, well imagine Luke crawling around digging through crates and showing an unhealthy fascination with a torch. They would probably also talk like Yoda, him being the only person they have ever conversed with. "Failed, Your Highness has.... a Jedi I am, like my father before me"