Episode 4 - Sand People attacking Luke as revenge?

I was rewatching Episode 4:A New Hope and was thinking that when the sand people attack Luke it could be seen as an act of revenge for what Darth Vader had done to their people during Episode II. Luke and Anikan look similar enough and Luke grew up on the same moisture farm so we should assume that the sand people that attack Luke are descended from or are from the same group that Anakin slaughtered. Although, Anakin claims to have slaughtered everyone including the children, but if that's the case then why are there sand people attacking Luke in the first place?