Why couldn't Luke and Leia of been the result of violence? An obsessive anakin being spurned by his crush tips over the edge goes dark side and forces himself upon her, she flees into hiding and has the children in secrecy.
Unpleasant sure but you wouldn't find Vader to be such a pathetic and whiny cry baby, as portrayed in the PT you don't fear him he's just a petulant child.
A **** would be much more dramatical and if they made her reject his feelings for years before that it would really be an actual reason for him to turn to the dark side in the first place (at least a better one than wanting to raise the dead or eternal life or whatnot he wants...) it would also explain much better why Padme does not want to live on. They could have made her give birth, and take her own life afterwards or something similar.
But honestly. A **** by a psychopathic wannabe Sith in a series of movie that is not only supposed to be for grown-ups but that has millions of children and adolescents for fans. That would just not feel right either!
Edited by ForceM