You raise an interesting point that is based in psychology. I do not have enough background in psych to know what drives the human instinct to embrace ‘bad’ behavior, but I have definitely seen nurture (what children see parents doing) have an impact on a child’s decision making. “The apple doesn’t fall far from the tree” is an expression that often explains a child’s behavior in some situations. This explains,partially, why your mother was surprised at the vampire game. I wonder when personality traits take a back seat to the basic need to survive. When we are faced with a choice that may result in our behaving badly, when do survival instincts kick in, even if we are only playing a game? I suspect there is ample research on this topic. I know from my own son’s experiences that there can be actual physical (medical) causes of inappropriate aggression. Once diagnosed, these are treatable, but undiagnosed can cause a child to behave in ways he or she would not ordinarily, and are deemed overly aggressive/mean. This topic has so many variables because humans are so complex.