the children of God can not be prossessed by satan but he can get in our head, and cause us to do things that will bring on bad things, if we walk in the flesh and not in the spirit we can bring on bad things to ourslves. The Blood of Christ covers our sins we have already sinned but it is up to us, Through the power of God, to give up present and future sins, Jesus came to take away the sins of the world, to give us dominion over sin and the flesh and satan. But we are weak, we hang on to alot of junk that we should be surrendering to Christ. Alot of different theories floating around as how to break family trait, family curses. But most agree it has to be through Jesus or in His Name that we break these things from us that hinders our walk with Him. but one thing I believe is that God gives us free will, in that we would in our sin nature, always do the wrong thing if we did not have free will, but as having free will,
God want take anything from us that we won't or that we are not willing to give up, and alot of times people will lay it at the feet of Jesus only to turn and pick it right back up. I don't know if your family has been cursed or not bit this one thing I do know if it has God can break it, for we all know
1jo 4:4Ye are of God, little children, and have overcome them: because GREATER IS HE that is in you, than he that is in the world.