1) Does silence or do heated verbal arguments evoke more fear?
Obviously, children are individuals. Therefore, each child could be affected in a different way by any given situation. All children are affected in some way by dysfunction in a family. Severe silence could make a child feel fearful of the unknown, unworthy of love or worthless as a person. Heated verbal conflicts, as well as silence, may create misplaced guilt in the child's mind. These verbally destructive episodes can create insecurities in relation to the child's parents. Do they love me? Am I causing this? However, fear may actually be greater during heated verbal arguments because there is much confusion, and there is always a possibility of an escalation towards violence. In fact, extremely heated verbal conflicts could be categorized as a violent behavior.
2) The roles the parents played in Ben's development:
One can only speculate unless there is access to an autobiography stating these effects. Some possibilities include the fact that there have been children who came from very dysfunctional families that who have determined later on to break the cycle, and they have become positive, caring people who advocate peaceful homes. They sometimes even become more successful in life because they are determined not to be like their parents. However, it is said that "adversity breeds character". In Ben Carson's case, the adversity of his youth led to an implementation of unconventional and drastic changes by his mother. Far less television and more reading affected Ben's life in a positive way. He flourished educationally when he gained knowledge and a sense of self-worth. His mother worked hard and, it seems, Ben may have learned her work ethic. She told her children that they were capable of the same things that rich children could achieve. She was an encouraging role model in this way. Her bouts with depression may have impacted Ben in a way that led him into a field that helps people medically. The role of Ben's father and step-father needs to be explored. However, again, children are individuals. Some pick up on the strengths of parents and discard the shortcomings. Other children could be devastated by on-going dysfunctions.
This is not a complete paper on the life of Ben and Curtis Carson. It is, however, food for thought and I hope it will lead you to think deeply about this answer and research his life.