Asteroid-Man said:

They know he's the offspring of Anakin - that would make him 24 or 25 wouldn't it? I think he'd know...

The son of skywalker.. Not anakin.Who is the papa skywalker is unknown and dead by vader. (ANH) We get the name anakin in ROTJ.

http://www.youtube.com/watch?v=rKtciRCVpFE&feature=related

SE messed with that for a more PT connection.

Palps wanted to seduct anankin for the imminent death of padme. He didnt mention about his kids. Otherwise if palps knew that he had children they would have obtain them asap. Ben mentions this plot in ROTJ too.

-Angel