killing younger sister

I have read an article about big brother killing younger sister and cutting her body apart. He killed his younger sister just beause she said "I have dreams, but you don't have any dreams. and you don't study, your dreams wouldn't come true." to him. I could hardly imagine it was the reason for a murder. It's just like kids arguing. Also, cutting the body... How could we do that? It's ridiculous. Family members should love each other, don't you think so?