[mom to 3]

Genetics are one of them, as well as, environment, trauma, nutrition, in utero exposure to alcohol and drugs.
I have two adopted children. One has been with us since age 5 1/2 and had experienced neglect, trauma and poor nutrition, in utero exposure etc. While he has had counselling and is a work in process, most of the time he is the best behaved of his friends. His bio brother has been with us since he was 4 days. He had limited supervised access that would not constitute trauma. He has been a handful since he could get around. His very determined and strong willed personality is very disruptive. He did have a time when he was returned to bio mom for 5 mths and did exp. real trauma then but most of his personality was visible before this event. I know that it was noticeable very early on. It must be due to genetics and exposure.

If we look at the characteristics that probably the parents had, poor impulse control, predisposition to addiction to alcohol or drugs, probable ADHD or ODD, then it is more likely that the children will possess some of these same issues. My family has some genetic issues too though and all we can try to do is help them learn to cope with their issues and be the best 'themselves' they can be.