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 .
The Science of Genetics and Behavior
It may seem obvious that the genes people inherit from their parents and share with their siblings have an effect on behavior and temperament. Individuals are often noticeably more similar in a variety of ways to immediate family members than they are to more distant ones, or to non-relatives. Of course, there are plenty of notable differences within families as well. Scientists have employed an array of methods to drill down into how and to what extent genetic differences truly account for psychological differences.
Behavioral genetics, or behavior genetics, is the study of psychological differences between individuals and how genetic and non-genetic factors create those differences. Among other questions, behavioral genetics researchers have sought to determine the extent to which various specific differences in people’s behaviors and traits can be explained by differences in their genetic code.
Scientists 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. Other methods, such as studying adopted children and their adoptive and biological parents, have been used as well. In recent years, genome-wide association studies (GWAS) have emerged as a major approach in behavioral genetics. A GWAS uses genetic testing to identify numerous genetic differences across many individuals , then analyze the association between these differences and personality traits or other outcomes.
Heritability is a measure of how much of the differences between people on a given characteristic can be attributed to genetics. More specifically, it is an estimate of the amount of variation between individuals in a given population that can be accounted for by genetic differences. Behavioral genetics research indicates that every trait is (at least) a little bit heritable —though the fact that a trait is heritable does not mean it is fixed.
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