Oh, right the twins.... I think their introduction was when the manga starting going down hill for me. I like evil stuff, but I feel the show makes their situation mellowdramatic, and that just makes me dislike the twins.
One girl's side of her body is scarred from a disease, and they make it seem like she's been to hell and back. One girl ate her mom, but tbf the entire clan was starving. Wasn't the now military leader avoiding eating so more food can go to the children? I wouldn't be surprised if others in the clan did cannibalism as well.
These two girls had their fair share of problems, but I feel the series blows it up more than it should.