With the significant recent advances in technology, one branch of genetics research has, over the past decade, increasingly focused on the possible genetic commonalities among those afflicted with psychiatric illnesses.  The center of attention has of course been the more disabling conditions: schizophrenia, bipolar disorder and major depression.   Much less work has been done as yet regarding the genetic predispositions and subsequent developmental processes related to personality.  Barbara Oakley's book, Evil Genes, reviews and summarizes much of the research available as of 2007, and goes on to generate her own ideas about what specific neurological processes could be involved in antisocial personality disorder and its cousins, narcissistic and borderline personality disorders.

Of course these were areas of interest for psychologists long before the possibility of genetic and neuroimaging research came on the scene. Personality in general and its problems in particular gained wide interest in the early 19000s, and were perhaps most popularized by the writings and lectures of Freud.  Since Freud's time there have been plenty of books written on psychopathy, specifically, as a personality formulation.  (For example, The Psychopathic Mind: Origins, Dynamics, and Treatment by Meloy, The Criminal Mind by forensic psychologist Katherine Ramsland , and, more recently, Evolutionary Forensic Psychology, edited by Duntley and Shackleford.)  But Oakley's book stands out for its breadth, its analytical (if necessarily speculative) review of pathological historic figures, and the inclusion of relevant characteristics, thoughts and behaviors of her now-deceased sister, Carolyn.

The use of her sister's personality and motivations brings home the point that the havoc created by those with antisocial personalities isn't just meaningful for historians, political scientists and film-makers — almost everyone has encountered people who are extraordinarily manipulative and self-serving.  Some of these people are obviously antisocial or sociopathic and can be readily avoided or managed, but many others can be charming and smoothly effective in achieving their goals despite the harm they cause to others.  Barbara Oakley's book is about this latter group: Machiavellians, aka the "successfully sinister."

Early in her book, Oakley notes that this sort of evil human nature "may be unavoidable and that it can have an unexpectedly good flip side" (p. 32).  However, the examples she provides in Evil Genes — Hitler, Joseph Stalin, Pol Pot, Chairman Mao and so on — give unclear examples of the good side, despite the charm that some of these despots were known to show in social situations — when it fit their needs or whims.  Still, Oakley is in agreement with evolutionary psychologists who believe this personality type no doubt arose and continues because it is somehow advantageous to human survival despite the troubles it causes to others, and the risks it presents for its bearers.  (Whether it continues to be adaptive in the nuclear age is another question entirely!)

In order to make sense of her theses, Oakley provides a very compact and useful overview of genetics and inheritance for readers unfamiliar with this area.  For example, citing work by twin researcher Essi Viding published in 2005, Oakley gives the estimate of inheritance for antisocial behavior at 81%, with the remaining 19% being attributable to environmental influences.  Other research referenced by Oakley showed that identical twins show a concordance rate of 35% for borderline personality disorder, while for fraternal twins the likelihood drops to 8%. (A study published in December 2008, not available at the time Oakley's book was finished, supports this level of concordance with a heritability estimate of 42% for borderline personality disorder in identical twins.  In fact, this recent study even reported specific genetic locations — linkages on chromosomes 1, 4, 9, and 18, with the strongest linkage on chromosome 9 at marker D9S286.)

As Oakley well explains, a central issue for personality is one's inherited capacity for mood management.  While environmental stressors are the triggers that lead to the development of the particular personality disorders considered here, the presumed genetic-neurological link is the switching on and off of genes that produce and modulate the brain's response to neurotransmitters, in this case serotonin.  In general, people with these personality disorders are unable to self-regulate mood in the same way that people without these disorders can.  Mood instability leads to impulsivity, and at the neurophysiological level, this involves the orbitofrontal cortex, the dorsolateral prefrontal cortex and the anterior cingulate cortex. Under the right (or wrong) conditions, impulsivity and mood instability, combined with power, are a potent recipe.

While of course no genetic or neurological studies were done of the dictators and despots to whom Oakley devotes entire chapters, she does provide plenty of historical evidence to illustrate their moodiness and cruel capriciousness, with implications for their mental functioning.  She also makes use of her intimate knowledge of her sister — partly based on her sister's diaries — to further illustrate how "regular" people may have these same tendencies, albeit of course with a much more limited field of action.

Although most readers of Oakley's book fortunately won't have direct experience of the larger-scale psychopaths, it's interesting to extend her ideas to the realm of everyday life.  Most of us will encounter plenty of our own petty tyrants (a term brought into common parlance by Carlos Castaneda):  out-of-control bosses, back-stabbing coworkers, neighbors who persist in outrageous behaviors, obnoxious or shamefully fickle relatives or in-laws.  While it's certainly bad form (and risky if done indiscreetly) to perform shade-tree diagnostics on such people, readers of Oakley's book will certainly have a lot to think about; perhaps it will provide a little comfort to have some theory at least about what's behind all the mayhem, but it's best to remember that at this point, most of our knowledge about the genetics of personality types should be considered provisional and exploratory.

Some of Oakley's ideas, syntheses and conjectures will be controversial, but the foundation of her thinking is quite solid.  The book is carefully researched, and its content ranges from genetics, neurology, historical review, forensic personality assessment, evolutionary psychology, ethics and free will, and more.   Although it occasionally deals with highly technical domains, Evil Genes is written in a conversational and accessible style, and both lay readers and specialists will find it informative and, despite its sometimes grim material, actually entertaining.

© 2009 Keith Harris

Keith Harris, Ph.D., is Chief of Research for the Department of Behavioral Health in San Bernardino County, California. His current interests include the empirical basis for mental health research, behavioral genetics, and the shaping of human nature by evolutionary forces.

Keywords: genetics, ethics