First of all, I’m really sorry that this is late. Being the scatterbrain that I am, I didn’t even realize that our first entry was due. So as I was thinking about the role of genes in controlling a person’s behavior and/or personality, it occurred to me that we didn’t discuss the profound effect that a single genetic mutation can have on a person’s appearance and personality. Consider Down’s Syndrome for example. Obviously every person with Down’s is a unique individual, yet they all share specific traits that in many ways come to define them. For example, most people with this syndrome are extremely social, upbeat, and exuberant. As most of you probably know, Down’s syndrome is caused by the duplication of chromosome 21. Although there are different mutations that can lead to this duplication, and the exact mechanism by which such a duplication leads to specific phenotypes is unknown, there is no question that the problem is genetic and that no amount of environmental intervention will prevent these phenotypes from occurring. While one could make the argument that the mutation itself could be caused by environmental factors, for example the age at which a mother conceives a child affects the likelihood that said child will be born with Down’s possibly because the maternal environment changes with age, the bottom line is that genes are responsible for Down’s Syndrome.
I know that this is an extreme example to bring to the nature/nurture debate, but I thought it was important to bring up. The subtleties of human behavior and personality are impossible to reduce to specific genes; I think in part because human beings are more similar to each other than we realize. Yet when it comes to the major aspects of a person’s physical appearance, personality, cognitive ability etc. are ultimately dependent on the “proper” functioning of genes.