I have not read this book, most I learned is from Edgar Cayce and H.C Randall Stevens.
Karma is cause and effect. Good and bad. That we 'forget' inbetween lives is a blessing. The burden would weigh very heavy on the present.To heavy.You will though discover your past in the future. There comes a time, when you know all, all will become clear.Till that time, let's just do our best...
I have observed with animals, that certain ticks, or bad habits are formed when another force is held from expressing itself. I think this is the same with us humans. If something is done against the nature of the person, against our programming, we will act upon it. Sometimes in life you will not know the why, when confronted with things of the past.
Cayce says that in every person we meet ,you meet a part of self, that needs to be harmonized. It is like magnets at work to balance the energy.
To come back to the addictive part, if addictive attitude takes up a great part of ones life,then most probably this person will not grow. The body is ones temple, and one does need to take care of it the best as we can.Likewise our thoughts, should be pure. Cayce states thought is the builder of everything. Thus it creates Karma.
Positive thinking is healing.