Sure, there was a connection in 1977 - and it worked well. However, other than something that took place many years earlier (see my signature), Vader & Luke were strangers, living different existences, Far Far Away from each other. I thought that Long Time Ago connection made for great motivation and tension when Luke decides to go to Alderaan after his family is killed.
Unfortunately, George doesn't know when to stop because he's not a talented writer. That coupled with his disturbing level of control issues makes for a tough task when trying to make a sequel to an already finished story.
He took a great, vast, dark, mysterious story (Star Wars 1977) and reduced it into a weak, weirdly incestuous, convoluted, Escher painting, that could have taken place in a solar system.
He told the story of Star Wars in 1977. For me, the problem became his deciding to tell it again in 1980, 1983, 1999, 2003, and 2005. Lucas insisted on taking an interesting character connection from 1977 and turning it into a 6-film franchise, spanning 28 years.
Weak.