The debate between what shapes who a person will become has been around as long as scientists have been around to contemplate it.  The biologists with their need to find a genetic link for everything use such genetic diseases as Down’s syndrome and Hemophilia to explain how nature develops the human adult.  The psychologists are never quite as absolute as the biologists and they have studies and Theorists such as B.F. Skinner to say that a person is only the result of how they are trained.  The reality of what shapes a person into the adult he becomes is actually a very well balanced blend of both. An adult person is made up of physical traits or characteristics, behaviors or habits and personality traits. Scientists and psychologists agree that physical traits and characteristics are almost entirely the result of genetics.  A person gets green eyes and blonde hair from a parent with green eyes and blonde hair.  If both parents are over six feet tall, the child will very likely be tall.  Additionally diseases such as Down’s syndrome, and color blindness are indisputably genetic.  Scientists have discovered specific genetic markers to identify how these traits and illnesses are acquired.  The debate comes in when the other aspects of a person’s make-up is questioned. When the origin of the way people act or behave is considered the debate begins to get very heated.  Most psychologists state that behavior is direct result of what people have learned during childhood.  The classical psychologists Skinner and Pavlov believed that every action a person made was learned.  They did experiments on animals to prove how stimulus affected and thus shaped behavior.  This attempts to dismiss serial killers as simply having bad childhoods (Powell, 2008). When the histories of many of the worst serial killers are investigated however, some had abusive childhoods and others had very nurturing childhoods.  Some studies done in Russian orphanages showed that much of what people learn comes from nurture. In these studies, a number of children spent months or years with very limited human contact.  The result was a group of children, who could not speak or interact with others.  These studies indicate there is a combination of both nature and nurture in behavior. When personalities come into the picture, the studies of twins who were raised in separate homes become a factor.  One of these studies was that of Elyse Schein and her twin sister, who upon their reunion discovered that over fifty percent of their personalities were the direct results of nature (Richman, 2007). This explains that the makings of a serial killer have to be a combination of genetics and the way a person is raised.  The twins in the study had no knowledge the other existed, but discovered they had a number of commonalities. The result of the years of study and debate comes down to the fact that a person is shaped both by who they are related to and how they are raised.  Neither bad genes nor bad caregivers can be blamed entirely for the end results of how a person turns out as an adult there is no evidence that people are shaped entirely by either, but there is evidence that both play significant roles. Resources: Powell, Kimberly, “Nature vs. Nurture” (2008) About.com. Retrieved January 31, 2008 from: Nature vs. Nurture - How Heredity and Environment Shape Who We Are Richman, Joe. “Identical Strangers”. (2007) excerpt from book by Elyse Schein. Retrieved January 31, 2008 from: NPR: 'Identical Strangers' Explore Nature vs. Nurture