In some Eastern traditions (as well as some Western metaphysical ones) your present circumstances are the effect of decisions and actions in past lives. If those were good decisions and actions, you have good experiences now, but if they were bad ones you have pain, suffering and sorrow now to the same degree you gave it out in one or more of those lives.
This is called Karma, a Sanskrit word usually translated as "cause and effect" or "reward and debt," but really means "action and reaction." The good actions you perform "now" create good karma and the bad actions you perform "now" create bad karma for your next lives. In these traditions karma isn't usually something you can change; all you can do is reap the rewards or work off the debts of the past.
One common Western tradition holds that you are rewarded in this life for obeying specific social or religious rules and punished in this life for breaking those rules.
Another, more modern Western tradition lays the praise or blame for your present attitude, actions and circumstances on heredity and your early social environment. The implication is that you were shaped by forces beyond your control and cannot be held responsible for what your genes, your parents, or society did to you.
Quantum Physics and the shamanic magic tradition are sharp contrasts to the above views. They say that the past did not give you what you have today, nor make you what you are today. But that it is your beliefs, decisions and actions today about yourself and the world around you that give you what you have and make you what you are.
Karma exists and operates only in the present moment. Your environment and circumstances in this moment are the direct reflections of your mental and physical behavior in this moment. Thanks to memory we may carry over habits of body and mind from day to day, but each day is a new creation and any habit can be changed in any present moment - although that doesn't meant it will be easy.
Your genes do not determine what you are or what occurs in your body. Instead, as an effect of your beliefs, you select out of the immense resources of your gene pool those characteristics that best reflect your present beliefs and intentions.
In the same way, your parents or social background have nothing to do with your present circumstances, but what you believe about them now and how you react to those beliefs now most certainly does. To the degree that you change yourself in the present moment - your thoughts and your behavior - you change your world.
Want to change your world, change your beliefs and change your mind.