Genetic Research in Psychiatry and Psychology

Abstract

IntroductionThe current consensus position in psychiatry and psychology is that, in addition to environmental factors, genes play an important role in causing psychiatric disorders and variation in ''continuously distributed'' psychological traits (such as personality and IQ). The fields of psychiatric genetics and behavior genetics have produced much of the research supporting this position, which consists of two broad areas of investigation. The first explores how a trait is distributed among various types of biologically related (and sometimes unrelated) people. The most common approaches have been the studies of families, of twins, and of people who have been adopted. These methods are sometimes grouped together under the heading kinship research. The second area is molecular genetic research, which attempts to pin down the actual genes that researchers believe underlie various traits and disorders.Contrary to most academic and popular accounts of this research, in this chapter we will see that studies of families, twins, and adoptees are greatly flawed on several critical dimensions. Moreover, countless sensationalized media reports notwithstanding, researchers have failed to discover the genes they believe underlie DSM-defined psychiatric disorders, and normal variation in psychological traits. Due to space considerations, we will look only at the most frequently cited research methods.If a trait is caused or influenced by hereditary factors, we would expect to find a greater concentration of it among members of the same family, roughly proportional to their degree of genetic relatedness. For example, first-degree biological relatives (such as the siblings, children, or parents of an individual) should manifest the trait more often, or resemble each other to a greater degree, than second-degree

The Genetics of Political Attitudes and Behavior: Claims and Refutations

“…Thus, for reasons having nothing to do with heredity, we should expect to fi nd a much higher "video game playing behavior" correlation in the United States among pairs of randomly selected 15-year-old boys than we would expect to fi nd among randomly selected pairs drawn from the entire 15-to 100-year-old male and female population of the United States (Joseph, 2010). This example illustrates one of the central fallacies of TRA studies.…”

“…What they actually must demonstrate-without qualifi cation-is that MZ and same-sex DZ twin pairs experience roughly equal environments. The validity of twin method can be determined only by assessing whether -not why-MZ twins experience more similar environments than same-sex DZs (see Joseph, 2004Joseph, , 2006Joseph, , 2010.…”

“…The argument, therefore, assumes the very thing that needs to be demonstrated. Thus, modern twin researchers (including twin researchers in the political science fi eld) circularly assume that twins' behavioral resemblance is caused by genetics in order to conclude that twins' behavioral resemblance is caused by genetics (Joseph, 2010) .…”

“…Critics, however, have pointed to several key methodological problems with TRA studies (TRA study critics include Farber, 1981;Joseph, 2001Joseph, , 2004Joseph, , 2010Kamin, 1974;Kamin & Goldberger, 2002;Lewontin, Rose, & Kamin, 1984;Taylor, 1980). These problems include (a) the doubtful "separation" of twins, who frequently grew up together and had contact over much of their lives, (b) similarity bias in the methods of MZA identifi cation and recruitment, (c) the questionable status of "intelligence" and "personality" as valid and quantifi able constructs, (d) the failure of the MISTRA researchers to publish or share raw data and life history information for the twins under study, and (e) the impact that the researchers' bias in favor of genetic interpretations may have had on their results and conclusions.…”

“…In order to control for the infl uence of cohort effects, a scientifi cally valid TRA study would compare the resemblance of MZA pairs reared apart from birth and unknown to each other versus a control group consisting not of MZT pairs but rather of genetically unrelated pairs of strangers who (a) are the same age, (b) are the same sex, (c) share the same ethnicity and culture, (d) share a similar socioeconomic status, and (e) are similar in appearance and attractiveness (Joseph, 2004(Joseph, , 2010. Moreover, both the MZA and the genetically unrelated (GU) pairs should have no contact with each other until after they are evaluated and tested.…”