A course I have attended says that the decisions we made in the past shape our future and can stand in our way. They used an example of a child who has one bad experience with a subject say maths, fails miserably or has a challenge they cant meet or overcome and decides that they are hopeless at maths and cannot do it. SO for the next 20 years when maths in involved the person fails in that area, avoids it like the plauge and so on. Yet when they examined that decision later on in life they discovered that infact they could do the math they thought they couldnt do and went into a completley different field, accounting and excelled at it. So that one decision shaped that persons life for 20 years. In this case you could definitely argue that the past shaped the future.
We also act from what we know from past experience. A simple illustration is that we learn from a young age that if we touch something hot we will burn ourselves, yet every child does it once. However that one experience taught us a valuable lesson that the average person learns from and that changes maybe future outcomes. So expereince does teach us and adds to our knowledge and helps shape who we are.
On a personal level I have had one very bad experience in relationships which now stops me from developing new ones and I am working on changing it, but experince has also tauight me that if you block people out of your life and you close your life to new experiences and opportuinties and people, you will have an empty uninteresting life, one could almost say half lived!
So yes I am the person I am because of my past, but I can choose to go beyond that past, learn lessons, take what I need from it but then I can move beyond it and in the future create a new past! I hope that makes some sense!