Okay, here goes. In Wolverine Origins, it is hinted that Logan and "Dog" (Possibly Sabretooth) have the same father. The alcoholic groundskeeper who resembles the adult Wolverine we all know. Now if Dog is in fact Sabretooth, this means they are brothers. However we do know that Sabretooths son is man that pushes the Friends of Humanity movement against mutants. He has no powers, and his mother is in fact Mystique, way to go! Later it was revealed that Sabretooth and Dog are in fact NOT the same person. In the film Wolverine X-Men Origins, them being brothers and life long war buddies was all Hollywood bull. The two didn't meet until around Vietnam.