Star Wars Eps VII Rumored Story Arc

Today an interesting rumor involving the possible story arc for Star Wars Episode VII did it's round on the internet (via schmoesknow) and it ivolved the Solo twins, Jacen and Jaina. Apparently someone had hold of some sort of "plot"  

"Two 17 year old twins, a girl and a boy, are trained by their uncle Luke to be the greatest Jedis in the galaxy. Problems arise when the male twin turns to the dark side". 

The only twins in the expanded univers are Jacen and Jaina Solo. I 've said that this would be the most plausible story arc from the beginning because it also would make the involvment of Mark Hamill, Harrison Ford and Carrie fisher more plausible, beside making one great story arc.

Jacen ( as well as Jaina ) is tought by Luke Skwalker in the ways of the the Jedi and turns to th dark side to become Darth Caedus.  His sister is to become one of the greatest Jedi's who ever lived

But... ( yes there's always a but) this is a very dark story line, one that doesn't have a happy Disney ending. And I think herein lies the problem, since Disney wants it to be a family film. So I wonder if they will see this through.  

Anyway it is all speculation at this point, and since nothing has been confirmed, accept the fact that J.J.Abrams is moving to London to start the roduction for Episode VII. So more on it as wel get.