The most common factors that influence one's behaviour are:
- The Environment he was raised in
A good example for this would be one who was spoiled by his/her parents while growing up. Giving in to ALL his/her wants. A child raised this way will likely end up being too "self-centered" as he is used to all the attention. Compare that to one who comes from a poor family and has to struggle in an early age just to survive. That child will likely end up as a "hardworking" adult as it is now imprinted in his thoughts that one needs to work very hard in order to survive in this cruel world.
- The Personality of the people raising him/her
One factor that needs to be considered is the personality of the people raising the child (mostly the parents). An abusive parent or a suicidal one will likely have a huge impact on the behaviour of the child in the future. He/She is most likely be traumatized and might even copy the behaviour of the people raising him/her. Violence breeds Violence.
- The Imposed Values he was raised in
What you teach a child at an early age will be his/her basis for what is right or good. If you impose on a child that "stealing", "cheating" or "lying" is wrong. Then at an early age, he will try his very best not to do those things. The lesson one learned as a child is likely what he will live for in the future.
You might be wondering why I am focusing mostly on how a child is raised during early childhood. This is mostly because at this age is where a child's personality will likely form. It is at this time that he starts to differentiate right from wrong and will mostly try to adapt base on this common factors.