Cursed from generation to generation

I've been reading through the old testament, and I have noticed more than once, God's promise to curse people far past their own generation. He promises to curse them from generation to generation. I've heard pastors speak on cycles of sin that permeate through families from generation to generation. I see it in my own family. It frightens me. Being one of the very few in my family choosing to walk in the Christian faith, I struggle with all that has happened within my family. Lying, cheating, stealing, alcoholism, drug addiction, murder. When and where does it end. I feel like my family is a microcosm of the world. My brother is going through hard times with his wife, and she is filing for divorce. He is making statements that sound so familiar and scary. So similar to what ran through my ears four years ago. I am powerless to stop anything from happening, and can only pray that he gets right with God and himself. I guess I need to come to terms with the fact that I cannot break the cycle for someone else, only for myself and my family. I see the difference in my life from my brother and my sister. I'm hopeful for them, and continually praying that things can change for them, but so much of it lies in their choices. They know the truth, but its a matter of choosing to do what they know is right. I can't tell them what to do. I can only pray.