xhonzi said:
Anakin couldn't have been 40 (or 30) during the PT. He had to be "closer" (C-3PO: "Closer?") to Luke's age so the Father/Son dynamic could play out.
Not true. See the Annotated screenplays. When they made ROTJ Anakin was intended to be in his 60s at the time of ROTJ (though the actor they cast was actually 77). If Anakin was in his 60s in ROTJ he would have been in his 30s or 40s when his children were born. So as you can see, Anakin WASN'T closer to Luke's age.
Once Anakin went dark, it's unlikely that Luke and Leia's mother would have stayed with him for long (he could have concealed his darkness from her for a bit, maybe, but I doubt that would last long). That means the conception of the twins would have been before he went dark or not too long after. So the twins' birth would have been not too long after he went dark (a few years at most). That he was dark once the twins were born is implied by a line Kenobi says to Luke in ROTJ. So Anakin went dark probably about 21 years before ANH or maybe a few years before that.
It should be remembered that anything Kenobi says about Vader and Anakin in ANH was written before the two characters were merged and thus may not be true of the backstory Lucas had at the time of ROTJ. For example, Kenobi describes Vader as being young when he betrayed the Jedi, helped kill them and killed Anakin. But at the time of making ROTJ Lucas clearly envisioned Anakin as being 30s or 40s when he turned. Even back when Lucas made ANH it is likely that he viewed Luke's father as not being so young, even though he clearly envisioned Vader as being young then. When the two characters were merged, Vader/Anakin was given the older age of the original Luke's father character (the Secret History of Star Wars goes into this stuff).
Perhaps (around the time of ROTJ) Lucas rationalized Kenobi's reference to Vader being young as another "point of view" thing. In the Annotated Screenplays we're told that Kenobi was envisioned as being about ten years older than Anakin (though if that's ANH Kenobi being ten years older than ROTJ Vader, that would really put Kenobi at 13 or 14 years older than Anakin, because there's a 3 or 4 year time difference between ROTJ and ANH). A Kenobi who was 10-14 years older than Anakin might view a 30s/40s Anakin as being "young", possibly, if you stretch it. Maybe Lucas did stretch it. Or maybe he just ignored the whole Vader being young discrepancy like he later ignored Leia's memories of her mother and other things .