The most common avenue to demonic entrance is through a family line. One person opens themselves to demonic influence and the demons claim them and all they have, including children. Then the same traits and influences pass on to the children and their children. Occult and Satanic involvement by activities, drugs, acid rock music, Ouija boards, etc. is another opening. Cult involvement in the family, especially Masons, opens one. The Bible says that when 2 people have sex the two become one flesh and that allows demons to claim the other person. Abuse of any kind or any form of trauma, especially when young, open one to the demonic. Strong soul ties with someone involved can cause an opening. Being unwanted when in the womb or young is a definite opening. These are some of the main avenues demons use to gain entrance and attack people.