When you go to God in earnest regarding if there is any sins between you and Him, He will open up your mind to incidents, and if you ask why, He will explain the root, seed, branches, and fruits of that event so that you can clearly see the atrocities that can go through the family into the fourth generation. When you see it the way God sees it, even "little" sins can have huge effects, and the repulsiveness of it will soon become clear. God is the only one who can truly help you see, and understand the depths of depravity, death, destruction, disease, and desolation that it can cause.