I have only watched the movie Scarface and not read up a whole on this topic other than what's posted on here. Scarface is one of my favorite movies and I have watched it several times. I see brothers' being protective of their sisters' all the time but not because of incest. I think Tony did not want his sister with a guy who did not respect her and he overreacted when he killed Manny, because he knew Manny was like him in ways. I think Gina was mad because he was trying to control her life so much, which is why she decided to shoot him, plus she probably wanted to anyway after he killed her husband. The chainsaw scene and all that is typical of the lives people lead when they sell drugs. If anything, I think the movie was not as violent as it could been. Where did you read all this stuff about Scarface from?