S_Matt said:

My challenge to those who don't buy Vader being Luke's father is to actually come up with a good argument against it

It's well documented in articles, interviews, web sites, & books that Vader wasn't Luke's father prior to Empire. To suggest otherwise is either revisionism or baiting.

In Lucas' original script (vision), Luke is in his 60s, Annikin is 18, and Darth Vader (first name, last name) is just a military general - not a Jedi, not a Sith. Three wholly separate and unrelated characters.

and you'll have to do better than..."George Lucas never intended".

People are free to dig or not dig the story as it was changed by Lucas in 1980, but to suggest that it was always his intention is incorrect.

http://secrethistoryofstarwars.com/

http://starwarz.com/starkiller/2010/05/the-origins-of-star-wars-the-evolution-of-a-space-saga/