This would be so interesting because he would get raised on Tusken cultural mores and also Tusken cultural memory, which means he probably does know a whole collective of Tusken people were essentially genocided something like three or four years before he was born, and it wasn't Darth Vader then, it was a guy carrying a lightsaber.
And then, of course, he meets Obi-Wan and gets the lightsaber so when he sees it he freaks the fuck out because, you know, cultural death icon, and Obi-wan is all "wtf" so Luke has to explain this to him and he's like "wtF???" because, like, he knows that Jedi don't do that so it's him and Luke now backtracking their way through a bunch of carefully preserved oral histories and a whole slew of rumours until they arrive at the time and place, which is, of course, a nexus near Owen and Beru Lars, who are super duper awkward about it, and while they don't know for a fact what happened, they definitely have enough dark suspicions that they just don't want to talk about it and find out that it's true.
But, you know, a mystical hermit and a Tusken have now shown up and their doorstep demanding answers and they really don't want any trouble, so they kind of reluctantly tell what they do know, and who was involved.
And then Obi-Wan turns and marches out into the desert without a word and somehow, Luke isn't sure how, just keeps walking until he finds the place, the ruins, barely extant in the shifting sands anymore.
"This is where," Obi-Wan breathed. "This was where he fell into Darkness. Right here, and so early. And I never saw it. I was blinded."
So Luke, who has been shadowing Obi-Wan all day and is getting increasingly worried about things like dehydration asks. "Who was he?"
And then Obi-Wan kneels down in the sand and say in a grim voice. "My student. My brother. Your father. In case you are wondering, that darkness in the air, that bleeds and screams? That's what you need to avoid."
Luke digests this silently.
Then he says "What an absolute bastard. Glad I'm not in that family anymore. I am a Tusken by rite, oath and deed."
Obi-Wan can admit, he has to kind of agree.