Monroville said:

Unless Skywalker was a common name, you think for as smart as Vader supposedly is, it would ring some bells. 20 some-odd years is not long enough to forget your entire first 20 years of existence, especially when it was defined by being pronounced the "chosen one" and finding the love of your life. You would think Vader would at least check it out... it's not like he had anything better to do, other than stand around making Tarkin look good.

If I also recall, didn't Shmi (or whatever Anakin's mothers name was) mention that Owen was her brother, and that is why Obi Wan gave Owen Luke to begin with? Of course, this conflicts with the ANH original story line that Owen was Kenobi's brother (King Arthur connection - Arthur was given to Kay's dad [can't remember his name] to take care of. At his coming of age, Arthur finds out that his "dad" is a surrogate and he is the true son of Uther Pendragon, who in the STAR WARS universe is still very much alive).

And now I've gone cross-eyed...

It has been a long time since you watched the prequels... Shmi married Owen's dad, making Owen and Anakin brothers. Uncle Owen is actually Luke's uncle, not "Uncle" Owen as had been assumed.