Genetic explanation of complex human behavior presents an excellent test case for pluralism. Although philosophers agree that successful scientific investigation of behavior is pluralistic, there remains disagreement regarding integration and elimination—is the plurality of approaches here to stay, or merely a waystation on the road to monism? In this paper we introduce an issue taken very seriously by scientists yet mostly ignored by philosophers—the missing heritability problem—and assess its implications for disagreement among pluralists. We argue that the missing heritability problem, (...) which isn’t going anywhere any time soon, implies that pluralism in behavior genetics is both practically ineliminative and theoretically non-integrative. (shrink)
Fisher’s 1918 paper accomplished two distinct goals: unifying discrete Mendelian genetics with continuous biometric phenotypes and quantifying the variance components of variation in complex human characteristics. The former contributed to the foundation of modern quantitative genetics; the latter was adopted by social scientists interested in the pursuit of Galtonian nature-nurture questions about the biological and social origins of human behavior, especially human intelligence. This historical divergence has produced competing notions of the estimation of variance ratios referred to as heritability. Jay (...) Lush showed that they could be applied to selective breeding on the farm, while the early twin geneticists used them as a descriptive statistic to describe the degree of genetic determination in complex human traits. Here we trace the early history of the heritability coefficient now used by social scientists. (shrink)
The fundamental reason that the genetics of behavior has remained so controversial for so long is that the layer of theory between data and their interpretation is thicker and more opaque than in more established areas of science. The finding that variations in tiny snippets of DNA have small but detectable relations to variation in behavior surprises no one, at least no one who was paying attention to the twin studies. How such snippets of DNA are related to differences in (...) behavior—known as the gene‐to‐behavior pathway—is the great theoretical problem of modern behavioral genetics.Given that intentional human breeding is a horrific prospect, what kind of technology might we want (or fear) out of human behavioral genetics? One possibility is a technology that could predict important behavioral characteristics of humans based on their genomes alone. A moment's thought suggests significant benefits and risks that might be associated with such a possibility, but for the moment, just consider how convincing it would be if on the day of a baby's birth we could make meaningful predictions about whether he or she would become a concert pianist or an alcoholic. This article will consider where we are right now as regards that possibility, using human height and intelligence as the primary examples. (shrink)
At the dawn of the new century, Robert Plomin was gloomy. As he recounts in Blueprint: How DNA Makes Us Who We Are, attempts to find the DNA responsible for the heritability of behavior failed. Month after month, journals would report new findings of specific genes for behavioral phenotypes, but they never replicated. One amazing genomic methodology after another was developed in biological genetics and applied to medicine, where it succeeded, and then to human behavior, where it failed. This was (...) the moment of Plomin's despair. He had, with great intellectual courage, staked his reputation on the existence of actionable scientific knowledge of the DNA‐based genesis of twin‐based heritability. But Blueprint is hardly the product of a gloomy author. Quite the opposite: it is a declaration of victory of nature over nurture, a celebration of the vindication of Plomin as a scientist and of behavior genetics as a field of study. What happened between 2000 and 2019 to brighten Plomin's outlook so radically? Were the genes for schizophrenia and intelligence finally discovered? Are we at last on our way to understanding why, at a biological level, all differences in human behavior are substantially heritable? Alas, no. What happened is that Robert Plomin gave up on the search for individual genes that explain heritability and decided to be satisfied with much less. (shrink)
In this consensus report by a diverse group of academics who conduct and/or are concerned about social and behavioral genomics (SBG) research, the authors recount the often‐ugly history of scientific attempts to understand the genetic contributions to human behaviors and social outcomes. They then describe what the current science—including genomewide association studies and polygenic indexes—can and cannot tell us, as well as its risks and potential benefits. They conclude with a discussion of responsible behavior in the context of SBG research. (...) SBG research that compares individuals within a group according to a “sensitive” phenotype requires extra attention to responsible conduct and to responsible communication about the research and its findings. SBG research (1) on sensitive phenotypes that (2) compares two or more groups defined by (a) race, (b) ethnicity, or (c) genetic ancestry (where genetic ancestry could easily be misunderstood as race or ethnicity) requires a compelling justification to be conducted, funded, or published. All authors agree that this justification at least requires a convincing argument that a study's design could yield scientifically valid results; some authors would additionally require the study to have a socially favorable risk‐benefit profile. (shrink)
The target article is skeptical of the heritability concept while maintaining an old-fashioned point of view about it. As a descriptive statistic, it is to be expected that heritability goes up and down in different circumstances, but the relationship between heritability coefficients and the biological processes that underlie them is difficult to specify, and may be impossible in humans.
The methodological shift from twin studies to genome-wide association studies (GWASs) diminished estimates of true genetic causation underlying statistical heritability of behavioral differences. The sum total of causal genetic influence on behavior is not zero, but, (a) no one cited in the target article ever thought this was the case, and (b) there is still little known about concrete instances of genetic causation.
The self allows us to reflect on our own behavior and to imagine what others think of us. Clinical experience suggests that these abilities may be impaired in people with personality disorders. They do not recognize the impact that their behavior has on others, and they have difficulty understanding how they are seen by others. We collected information regarding pathological personality traits—using both self and peer report measures—from groups of people who knew each other well . In previous papers, we (...) have reported that agreement between self-report and peer-report is only modest. In this paper, we address the question: Do people know that others disagree with their own perceptions of themselves? We found that expected peer scores predicted variability in peer report over and above self-report for all 10 diagnostic traits. People do have some incremental knowledge of how they are viewed by others, but they do not tell you about it unless you ask them to do so; the knowledge is not reflected in ordinary self-report data. Among participants who expect their peers to describe them as narcissistic, those who agree with this assessment are viewed as being less narcissistic by their peers than those who deny being narcissistic. It therefore appears that insight into how one is viewed by others can moderate negative impressions fostered by PD traits. (shrink)