Behavioral genetics is a field of study which deals with animal behaviorism as an attribute of genetic inheritance. To what degree are the attributes of human persona and mannerism the result of developmental and environmental influences and to what degree are they inherited from our parents? It is a difficult question to answer.
In the 1940's, researcher Robert Tyson discovered that the offspring of rats that had learned to run a maze seemed to have inherited the ability from their parents. Did this suggest that intelligence could be inherited? A whole lot of neuroscientists were beginning to consider the possibility. Since then the field of genetics has undergone a transformation of revolutionary proportions. Today geneticists are considering the implications of individual genes in human and other animal DNA, and yet the elusive smoking gun that would support any contention that behavioral traits are inherited remains elusive.
The study of identical twins, those who's genes are 100 percent equivalent, has provided the best opportunity to study not only genetic influences on behaviorism, but environmental factors as well. One might presume, that if behavioral patterns are inherited, that this would be true 100 percent of the time, and that identical twins would be behaviorally identical as well. In reality this is not the case. What researchers in the field have determined, is that while genes play a significant roll in establishing a predisposition favoring a given behavioral trait, they do not specifically influence the predominance of the trait in an offspring. Environmental influence seems to be at least a secondary factor.
Since the human genome was sequenced in 2000, the ability to investigate specific genes has opened the door to new fields of genetic research, including a new discipline called epigenetics. This field of study considers both the effect of genes with respect to heredity as well as the effect of environmental influences on genetic metamorphosis. Recently, some vary amazing things have been learned that are going to radically alter perceptions with respect to genetics including behavioral genetics. For instance, genetic mutation has been previously thought of as an aspect of conceptual incipience and that once the union of maternal and paternal progenitor DNA has taken place, the genetic blueprint remains static for the rest of the individuals life. New evidence uncovered by epigeneticists clearly contradicts this notion, suggesting that our DNA is much more dynamic and subject to environmentally induced polymorphism.
At very least, this new epigenetic evidence adds a whole new parametric of genetic complexity to the equation of inheritance. Ironically, it also lends credence to the Twinkie defense, a concept synonymous with the murder trial of Harvey Milk in 1979. Psychiatrist Martin Blinder offered as testimony for the defense, that Milk's diet of sugar laden junk food had resulted in an incidence of aberrant psychosis in Milk, contributing to his apparent status of madness and commission of a heinous crime. The early evidence uncovered through epigenetic research has shed new light on environmental factors as strongly influencing genetic amorphousness. Whether this translates into any effect with respect to behavioral genetics, while such consequence is strongly implicated, it has yet to be confirmed.
The study of behavioral genetics has been ongoing for more than a half a century, but rather than reaching any conclusion with regard to the nature verses nurture argument from a behavioral perspective, this area of research has only generated a gauntlet of new questions to be addressed. Taking into consideration the latest epigenetic evidence, it would seem that behavioral genetics has found itself back on square one and starting all over again.