The Role of Genetics in Shaping Psychological Diseases Such as Clinical Depression
A friend says, " My mother suffers from clinical depression. I know I will, too û itÆs in our genes." While such a fear is understandable, in responding to it one must consider both the complicated nature of the way genes are expressed and the roles played by both genetics and the environment in shaping a personÆs psychology. In looking at the many possible influences on a personÆs psychological makeup, it becomes clear that while genetics is an important factor, the role of social environment and personal choices presents the possibility of modifying an individualÆs present and future psychological state.
Any trait in an individual is guided to some degree by his or her genes. Parents transmit genes to their offspring via chromosomal DNA, which contains information to guide the offspringÆs development. A sequence of DNA that encodes for a particular protein is called a gene. This simple information-carrying system, possessed by every cell in the body, is made far more complex by the way genes can recombine when they are passed on as well as the way they are expressed in the offspringÆs phenotype, or outward presentation.
For example, the predisposition for a psychological trait such as clinical depression may be carried by the mother only and be absent in the father. The offspring of these parents is said to be heterozygous for this trait. A particular gene from one parent only is called an allele. Thus it is possible that the friend who is afraid of becoming clinically depressed based on the expression of this trait in the mother actually has an allele for this gene from the mother only but does not have it from the father. If the fatherÆs allele is recessive, the friend may not have a genetic predisposition to becoming depressed at all. There are many other scenarios in which the phenotype of a parent does not guarantee the express...