As members of one species, we humans share both a common biology (cut us and we bleed) and common behaviors (we similarly sense the world around us, use language, and produce and protect children). Our human genes help explain our kinship—our shared human nature. And they contribute to our individual diversity: Some people, compared with others, are taller, smarter, skinnier, healthier, more temperamental, shyer, more athletic . . . the list goes on and on. Across generations, your ancestors shuffled their gene decks, leading to the hand that—with no credit or blame due you—you were dealt. If you are reading this, it’s likely that genetic luck contributed to your having above average intelligence. Others, dealt a different hand and a different life, would struggle to understand these words. Andrew Brookes/Image Source/Getty Images Individual variation is big. Individuals vary much, much more within groups (say, comparing Danes with Danes or Kenyans with Kenyans) than between groups (as when comparing Danes and Kenyans). Yet there are also group differences. Given this reality (some groups struggle more in school), does behavior genetic science validate ethnocentric beliefs and counter efforts to create a just and equal society? In The Genetic Lottery: Why DNA Matters for Social Equality, University of Texas behavior geneticist Kathryn Paige Harden answers an emphatic no. She documents the power of genes, but also makes the case for an egalitarian culture in which everyone thrives. Among her conclusions are these: We all are family. Going back far enough in time to somewhere between 5000 and 2000 B.C., we reach a remarkable point where “everyone alive then, if they left any descendants at all, was a common ancestor of everyone alive now.” We are all kin beneath the skin. We’re each highly improbable people. “Each pair of parents could produce over 70 trillion genetically unique offspring.” If you like yourself, count yourself fortunate. Most genes have tiny effects. Ignore talk of a single “gay gene” or “smart gene.” The human traits we care about, including our personality, mental health, intelligence, longevity, and sexual orientation “are influenced by many (very, very, very many) genetic variants, each of which contributes only a tiny drop of water to the swimming pool of genes that make a difference.” Individual genes’ tiny effects may nevertheless add up to big effects. Today’s Genome Wide Association Studies (GWAS) measure millions of genome elements and correlate each with an observed trait (phenotype). The resulting miniscule correlations from thousands of genetic variants often “add up to meaningful differences between people.” Among the White American high school students in one large study, only 11 percent of those who had the lowest GWAS polygenic index score predicting school success later graduated from college, as did 55 percent of those who had the highest score. “That kind of gap—a fivefold increase in the rate of college graduation—is anything but trivial.” Twin studies confirm big genetic effects. “After fifty years and more than 1 million twins, the overwhelming conclusion is that when people inherit different genes, their lives turn out differently.” Parent-child correlations come with no causal arrows. If the children of well-spoken parents who read to them have larger vocabularies, the correlation could be environmental, or genetic, or some interactive combination of the two. Beware the ecological fallacy (jumping from one data level to another). Genetic contributions to individual differences within groups (such as among White American high school students) provide zero evidence of genetic differences between groups. Genetic science does not explain social inequalities. Harden quotes sociologist Christopher Jencks’ illustration of a genetically influenced trait eliciting an environmentally caused outcome: “If, for example, a nation refuses to send children with red hair to school, the genes that cause red hair can be said to lower reading scores.”  Harden also quotes social scientist Ben Domingue: “Genetics are a useful mechanism for understanding why people from relatively similar backgrounds end up different. . . . But genetics is a poor tool for understanding why people from manifestly different starting points don’t end up the same.” Many progressives affirm some genetic influences on individual traits. For example, unlike some conservatives who may see sexual orientation as a moral choice, progressives more often understand sexual orientation as a genetically influenced natural disposition. Differences ≠ deficits. “The problem to be fixed is society’s recalcitrant unwillingness to arrange itself in ways that allow everyone, regardless of which genetic variants they inherit, to participate fully in the social and economic life of [their] country.” An example: For neurodiverse individuals, the question is how to design environments that match their skills. Behavior genetics should be anti-eugenic. Advocates of eugenics have implied that traits are fixed due to genetic influences, and may therefore deny the value of social interventions. Alternatively, some genome-blind advocates shun behavior genetics science that could inform both our self-understanding and public policy. Harden advocates a third option, an anti-eugenic perspective that, she says, would reduce the waste of time and resources on well-meaning but ineffective programs. For example, by controlling for genetic differences with a GWAS measure, researchers can more accurately confirm the actual benefits of an environmental intervention such as an educational initiative or income support. Anti-eugenics also, she contends, uses genetic information to improve lives, not classify people, uses genetic information to promote equity, not exclusion, doesn’t mistake being lucky in a Western capitalist society for being “good” or deserving, and considers what policies people would favor if they didn’t know who they would be. Harden’s bottom line: Acknowledging the realities of human diversity, and discerning the powers and limits of various environmental interventions, can enhance our quest for a just and fair society. (For David Myers’ other essays on psychological science and everyday life, visit TalkPsych.com. Follow him on Twitter: @davidgmyers.) ... View more

Judith Rich Harris’ December 29th death took my mind to her remarkable life and legacy. Among all the people I’ve never met, she was the person I came to know best. Across 243 emails she shared her draft writings, her critical assessment of others’ thinking (including my own), and the progress of her illness. Our conversation began after the publication of her cogent Psychological Review paper, which changed my thinking and led me to send a note of appreciation. The paper’s gist was delivered by its first two sentences: “Do parents have any important long-term effects on the development of their child’s personality? This article examines the evidence and concludes that the answer is no.” Her argument: Behavior genetics studies (of twins and adoptees) show that genes predispose our individual traits, and that siblings’ “shared environment” has a shockingly small influence. Peers also matter—they transmit culture. Show her some children who hear English spoken with one accent at home, and another accent at school and in the neighborhood, and—virtually without exception—she will show you children who talk like their peers. Judy Harris was a one-time Harvard psychology graduate student who was dismissed from its doctoral program because, as George Miller explained to her, she lacked “originality and independence.” But she persisted. In her mid-fifties, without any academic affiliation and coping with debilitating autoimmune disorders, she had the chutzpah to submit her evidence-based ideas to Psychological Review, then as now psychology’s premier theoretical journal. To his credit, the editor, Daniel Wegner, welcomed this contribution from this little-known independent scholar. Moreover, when her great encourager Steven Pinker and I each nominated her paper for the annual award for “outstanding paper on general psychology,” the judges selected her as co-recipient of the—I am not making this up—George A. Miller Award. (To his credit, Miller later termed the irony “delicious.”) The encouraging lesson (in Harris’ words😞 “‘Shut in’ does not necessarily mean ‘shut out.’” Truth will out. Although biases are real, excellence can get recognized. So, wherever you are, whatever your big idea or passion, keep on. Her fame expanded with the publication of her 1998 book The Nurture Assumption, which was profiled by Malcolm Gladwell in a New Yorker feature article, made into a Newsweek cover story, and named as a Pulitzer Prize finalist. Her argument was controversial, and a reminder that important lessons are often taught by those who fearlessly push an argument to its limit. (Surely child-rearing does have some direct influence on children’s values, religiosity, and politics—and not just via the peer culture to which parents expose children. And surely the loving versus abusive extremes of parenting matter.) Harris was kind and generous (she supportively critiqued my writing, even as I did hers) but also had the self-confidence to take on all critics and to offer challenges to other widely accepted ideas. One was the “new science” of birth order, which, as she wrote me, was “neither new nor science.” An August 24, 1997, email gives the flavor of her wit and writing: Birth order keeps coming back. In their 1996 book on birth order and political behavior, Albert Somit, Alan Arwine, and Steven A. Peterson spoke of the “inherent non-rational nature of deeply held beliefs” and mused that “permanently slaying a vampire”—the belief in birth order effect—may require “that a stake of gold be driven through his/her heart at high noon” (p. vi).             Why is it so difficult to slay this vampire? Why, in spite of all the telling assaults that have been made on it, does it keep coming back? The answer is that the belief in birth order effects fits so well into the basic assumptions of our profession and our culture. Psychologists and nonpsychologists alike take it for granted that a child’s personality, to the degree that it is shaped by the environment, receives that shaping primarily at home. And since we know (from our own memories and introspections) that a child’s experiences at home are very much affected by his or her position in the family—oldest, youngest, or in the middle—we expect birth order to leave permanent marks on the personality.             The belief in birth order effects never dies; it just rests in its coffin until someone lifts the lid again. Alas, the disease that shut her in has, as she anticipated, claimed her. In her last email sent my way on September 6, 2018, she reported that I’m not doing so well. This is the normal course of the disorder I have—pulmonary arterial hypertension. It is incurable and eventually progresses to heart failure and death. I’m in the heart failure stage now. It’s progressing very slowly, but makes remaining alive not much fun.              Because I can’t actually DO anything anymore, it’s a treat to get your mail. I can’t do any more than I’ve already done, but maybe what I’ve already done is enough. Who would have thought that 20 years after its publication, people would still be talking about The Nurture Assumption! Or that The New York Times would replay its message at length, in your well-deserved obituary, Judy. (For David Myers’ other essays on psychological science and everyday life visit www.TalkPsych.com.) ... View more