Two children were born into an abusive family. They were fraternal twins, and born at least fifteen years after their parents’ first child. Both grew up in the same house with the same ornery, alcoholic father and strict, unforgiving mother who often resorted to violence as a means of punishment. The twins were emotionally neglected and probably could have had better parents if the mother and father each transmogrified into a different type of rotten fruit. This will be case A.
In case B, another pair of fraternal twins was raised by an alcoholic mother and violent father, and had a much older sibling. Case C is identical to case A except the C parents annually made 200 thousand dollars more, and in case D the fraternal twins were raised by a rusty can and a turtle. Which of these four environments would most predictably elicit consistent aggressive, antisocial behavior in the respective sets of twins? Go ahead, guess.
If you chose any of them, you’d be wrong. It may very well be that all, none, or most of the cases above besides the can/turtle scenario produced callous, antisocial children, but no direct correlation exists. The behaviors the fraternal twins watch their parents perform consistently certainly impacts the children, but in no one specific way. Why not?
The process by which humans learn their behaviors and beliefs from the myriad environments each encounters as he develops–socialization–is simple to conceptualize, but inherently difficult to quantify. In the first case, it could have also been stipulated that one of the twins were homeschooled while the other attended public school regularly. The homeschooled twin spent disproportionately more time watching his parents interact with each other–watching them fight, curse, and attempt to inculcate within their child a dubious moral code while in a drunken haze–and the other twin spent each day watching how other kids his age interacted with one another. One day during kindergarten, the public-schooled twin noticed that whoever last left the classroom would have the teacher ask him to help clean up for a few minutes. Impatiently and consequently, he diverted more energy towards ensuring he wasn’t the last to leave; however, he saw that a couple of the other children scrambled more quickly than he did–more quickly than he could–to escape the room before they were the last and had to stay past the end of the school day. Feeling abandoned by his parents because he was stuck trying to run away from extra cleaning all on his own while his brother was homeschooled, he felt his only recourse was to take matters into his own hands, and he therefore began to start hiding his classmates’ belongings so they would have to spend the time he used to pack up and leave looking for their own things.
About a decade later, the same boy’s sibling, no longer homeschooled, rode the school bus everyday to high school, where he discovered that some of his peers more readily spent time with him if he could make them laugh. He wasn’t exactly sure how to do that, so he experimented with various styles of humor–slapstick, deadpan and the like–until he discovered that deprecating jokes almost universally elicited some giggles. Insults were, of course, fairly empty (if not downright stupid) without substance, and so there had to be a way for him to reconcile the need to make people laugh with his utter lack of knowledge about his peers. So he thought of his brother, the wunderkind who simultaneously smiled, did well in class, and went to parties every few weeks, and he came to conclude that he could joke about the brother who poorly rapped Eminem songs alone in his room. His brother’s idiosyncrasies were a hit with his friends, and as he become more comfortable around other kids his age, the deprecating humor gradually came to an end.
Another decade after that, the initially-homeschooled twin still lived with his parents while the publicly-schooled twin was a clever, successful accountant with an above-entry-level job at a firm in New York City. The latter brother had been working at the firm for almost two years, and he had been promoted thrice. He worked, on average, about forty hours each week, and had rented an apartment a few blocks from his job with a roommate he met in high school. The former twin spent most of his time writing fruitlessly in his bedroom, and usually fancied himself a published author–although he was not once–when he went out with acquaintances and the few friends he had managed to hold onto. He rarely spoke with his parents. Six months from this point in the twins’ lives, the homeschooled twin will finally finish and publish his first collection of short stories, and the accountant-twin will commit suicide.
What detail from this brief account of the two lives would lead anyone to conclude that one of the two boys eventually kills himself? Is the relevant detail even mentioned? Is there even a specific event that would have engendered it. Perhaps his job was too high stress and his aloof and distant parents hadn’t helped him learn how to cope, although it could be said that other accountants who had similarly negligent parents lived long and somewhat comfortable lives. Or, perhaps, one day he drank too much, remembered reading a story, years ago, about a girl who committed suicide, and was suddenly inspired. There are far, far too many confounding factors that make such conclusions almost impossible to draw, but it can, at least, be said that there are some genetic and environmental circumstances that will definitively impact someone’s socialization. For example, if the two twins were identical instead of fraternal (if they were monozygotic rather than dizygotic), it would have been more likely that both twins would have more readily exhibited aggressive, emotional behavior or that neither of them would. It is, of course, true that development due to the environment–ontogeny–could and does easily impact how aggressively anyone will act, and there is a more general, physiological description of the likelihood of aggressive, impulsive behavior than the identical twins scenario.
The ventromedial prefrontal cortex, the vmPFC, and a region of it known as the subgenual anterior cingulate cortex play a special role in inhibiting emotional responses: the vmPFC accepts input from the dorsomedial thalamus, olfactory system, temporal lobe, and the amygdala. From these regions, it receives information regarding the environment and what plans the other regions of the cerebrum are currently making, and outputs to regions such as the hypothalamus and amygdala in a way that allows it to affect emotional responses, often through inhibiting them. It’s the region of the prefrontal cortex that essentially checks aggressive, antisocial, impulsive, emotional, or violent behavior, if the behavior is inappropriate in a real, personal context. There was a man in the mid-1800s named Phineas Gage, who suffered from an accident involving a steel rod that exploded forward, through his cheek, and up out of his skull. He lived, but he was different. Before the accident, he was focused and had a good work ethic, but afterwards he became callous, irresponsible, and prone to emotional outbursts. Guess why.
The steel rod had destroyed most of his vmPFC, and as a result he acted much more impulsively, and also became almost entirely unable to make or keep plans. The region of his brain that once held his hand and sternly whispered in his ear don’t had been gimped. Of course, those who suffer from accidental impalements aren’t the only ones who act childishly, and so another explanation is possible. In London, cab drivers were once required to learn whole maps of London so they could get around more quickly, and it was shown that this requirement caused their cabbies’ brains to devote more neurons to the spatial memory center, the hippocampus. On average, London cab drivers have significantly larger hippocampi than you or I would. As discussed in the post Moral Dilemmas, children are more prone to emotional outbursts because their vmPFCs have not yet sufficiently grown as to more successfully inhibit the amygdala and the impulsive behavior it helps engender. Here lies perhaps the only quantifiable aspect of this discussion on anger and aggression: the bigger the vmPFC, the less likely a volatile reaction will occur.
Andrew Speers
