Why Is Genetics Important?
Genetics is the study of genes and the variation of characteristics that are influenced by genes—including physical and psychological characteristics. All human traits, from one's height to one's fear of heights, are driven by a complex interplay between the expression of inherited genes and feedback from the environment.
Many genes interact to influence the human brain. Almost all normal and disordered characteristics are polygenic, meaning that they are each shaped by a large number of genes.
Scientists are tasked with a massive but increasingly plausible mission: mapping the pathway from one's genes to the person one sees in the mirror. What they learn about the power of genes has implications for understanding mental illness and psychological differences between individuals, as well as the psychological effects of non-genetic factors.
Epigenetics involves the study of how non-genetic factors (including environmental and experiential ones) modify the influence of genes.
Why Do Genes Matter in Psychology?
Genes help to define who an individual is inside and out. In addition to visible traits like weight and eye color, psychological qualities such as personality traits, intelligence, risk of mental illness, and more have been linked to genetics. Non-genetic factors have a role to play, too, but what scientists have learned about how genetic and non-genetic influences play out can clash with common wisdom.
A characteristic or behavior that appears to result from a child’s upbringing—such as a proneness to mental illness or divorce—may actually be largely a product of the genes she inherited from her parents. In fact, research investigating the influence of the family environment suggests that it accounts for a surprisingly small amount of the difference between people on characteristics that scientists measure.
Behavioral scientists and behavioral geneticists use specialized methods to explore the links between genes and individual differences. Studies of twins who either do or do not have identical genomes allow for estimates of the degree to which genes drive the variation in psychological traits. In recent years, genome-wide association studies (GWAS) have surpassed twin studies as the most revelatory means of investigating behavioral genetics. A GWAS allows scientists to identify numerous genetic differences across many individuals, then analyze the association between these differences and personality traits or other outcomes.