The environment in which the brother grew up would have a significant impact on his response to any jealousy he felt about his sister receiving more attention. To some extent, children learn how to respond to events in life from the way people around them behave. So a child growing up in an area with very little violence would tend to be much less violent than a child growing up in a violent area (all else being equal).
What ever town he grew up in he would have grown up in a wealthy area in a wealthy family with wealthy neighbors. Areas of town like that tend to be low crime.