Does your past make you into who you are today?

Does your past make you into who you are today? I believe 100% it does.
A few years back I came to this cross roads in my life. I could either live in the past or use the past to form me into a better person. I chose to use it not to let it use me. As a young child I knew that I had been thru a lot. I knew that I wanted to go into Psychology to help children face head on what they are going thru and not to feel alone. This is what I did up until I had my oldest. I worked in a locked down facility for court ordered girls and a metal facility for children and adolescents.
Let me back up a little...My parents divorced when I was in the 3rd. grade. It was a NASTY divorce. Cheating abuse you name it I am sure it was involved in the failure of their marriage. Thru the years many things happened. My dad ended up being admitted to a mental hospital (ironically I ended up working in that same place as an adult)I saw my father try to kill himself, I also witnessed him trying to run my mom over with a car with me in it. Don't think my mom was innocent in all this she wasn't. My sister and I were young and we dealt with things in the best way we could. I bottled things up and knew one day I would make a difference with mine. My sister on the other hand turned hers into hatred and anger.
Shortly before I had my youngest my mother was on the brink of a complete break down. I was watching it happen. Finally I went to her and told her she needed help. This was my field I knew what I was talking about. She finally agreed and got help from her family doctor. Her doctor sent her to a psychiatrist. This new doctor I loved. She told her everything I had said. Coming from me my mom was OK with me saying she hadn't dealt with the past (DIVORCE 20 some years ago.) And she was under great stress with living with my grandparents. Coming from this new DR she wasn't. Needless to say she never returned. She decided she would talk to me about this. For about 1 month I let this go on. But it was weighing me down big time. While I am an adult now I don't want to know or can I properly deal with adult issues from my childhood nor do I want to. I have dealt with what I needed to. I had to explain to my mom that I wasn't the person to talk to about this. She needed a Doctor that was neutral. Fast forward to the past 6 months. My sister has been in town due to her husband being in Iraq. She lives in the past. She seams to LOVE talking about it. Every time we are in the car or alone she seams to bring it up. How bad life was, how she was so mistreated. 99% if the stuff she says isn't true. Sure enough every time she brings this up something new comes up. Today is my final straw. She proceeds to tell me that when she was 11 she tried to hang herself to give me a family and I walked in on it. WTF. Really I don't want to deal with this anymore. I told her that I am done dealing with the past. It isn't productive.
I went on to tell her that I truely believe that EVERYTHING happens for a reason. I told her that all the stuff from my childhood happened so that I could understand and help a child in a way that most can't. I just don't think she understands. I really think that she likes to live in this misery but I can't. I have faced my past with open arms. I understand it for what it is. Not for what it was. I love my parents I don't always agree with what they have done and still do.
Am I the only one that has to deal with these issues as an adult. It seams like the demons from the past come from every direction sometimes. Sorry if I have shared to much information. But I so needed to talk about it. I was laying in bed and couldn't sleep because all of this needed to come out. And well since Mommy Confessions never sleeps why not share it her.