I believe that once a person has been exposed to the abuse, it changes them and turns things around in their head. What was suppose to be sacred about their bodies has been violated and because of this it makes it easier for them to violate someone else, it is familiar to them. There is also anger that is associated with being abused and that may also trigger them to abuse.
Anyone who has been abused should seek professional help so that they can understand the complexity of what it does to the mind and body. The mind in a way needs to be reset and the thoughts and feelings that the abused person has need to be changed into a survival mode instead of a victim mode. The power has to be given back to the victim in order for them to heal.