i hate watching movies based on the comics, they fucked the wolverine story so bad.
wolverine did have a brother, but it wasn't sabertooth. plus wolverines brother started the weapon X program.
in Wolverine:The End you find out about his brother and you find out about wolverines son and his defaction from the x-men, with a slew of other things too.
also in concerning wolverine and sabertooth, they were in no ways related. in fact, they were both thought to be advancedhumans rather than mutants, but sabertooths appearance seemed more mutant than anything else. turns out the wolverine was part of a wolf-clan as where sabertooth was part of a bear-clan, whereas they hated each other naturally.