Half Bros
I think owen had a diffrent father,or they weren't related what so ever. I think where OB1 is from may not come up at all.I speculate that if his origin comes up it will be Corellia because that seems to be one of the few human populated Republic planets close to Coruscant.Maybe Dantooine could be possible or Malistaire.
Re: Half Bros
A reason why Owen and OB1 aren't brothers, is because don't you think Owen would have sensed the arrival of stormtroopers and panicked? I mean, OB1 was a jedi, even though Owen wasn't trained he can still sense good and evil. If they are brothers they either have different mothers or fathers. But then that puts a groggy feeling in me thinking one of OB1's parents was a sex fiend.
half brothers
my guess is that they are not related in any way shape or form. they told luke that owen was his uncle. wrong. besides, if obi-wan did have a brother and anakin knew about it don't you think anakin (aka darth vader by that time) would have tried to find him as leverage in getting his kidnapped son back from obi-wan? i say that obi-wan just "said" owen was his brother, like he "said" owen was luke's uncle.
alternative hypothesis. owen isn't the relative, but the inlaw. could he have married beru kenobi??
I liked the idea mentioned that Owen is an adopted son of Schmi. When Anakin returns to save his mom she is killed(probably by the new sith apprentice with Fett's assistance), he ends up saving from slavery and befriending Owen. Both feed off each others anger at Schmi's death, and Owen can tell Ani what became of Schmi in the years after Ani left. Owen goes with Anakin on business at Coruscant. Owen tolerates the strict older Obi-wan but he creates a rift in OB1 and Ani's friendship. Owen meets Beru on Coruscant. Beru is a friend of Bail's from Alderann, kind and loving the two hit it off. Owen is prominent during OB1 and Anakin's deterierating friendship, fun loving and laid back Owen is horrified to see Anakins transition to Darth Vader. Somehow Darth must be under the impression Owen is killed, Owen is traumatized and retreats to Tatooine to be a farmer and never get involved. Obi-Wan and Owen were never friends but OB1 asks Owen and Beru who can't have children to raise Luke, telling him that they are his Aunt and Uncle. Vader thinks Owen is dead and Obi-Wan retreats nearby to observe Luke.
Re: Master Qui-Gon Jinn would NEVER have sex with Shmi
Owen Lars is Obi-Wans brother. If you read the script for ROTJ it tells you. The scene where Obi-Wan explains everything to Luke on Degobah has Obi-Wan telling Luke this.He also says a lot of other stuff but most of it was cut out in the final film. You can get the script from lots of web sites.