Evolutionary biology, it should be said at the outset, is in play throughout The Origins of You. It’s central to attachment theory, which studies all aspects of the parent-child bond and has weathered seismic shifts in psychology ever since John Bowlby proposed it more than half a century ago. In 2008 or so, principal author Jay Belsky, who teaches human development at UC Davis, drew attention to the understudied significance of genetics and genomics for the theory, and this book unpacks what prior and subsequent research has wrought. It ranges across disciplines. With respect to behavior, and whether children thrive, get by, or fall victim to circumstances, the authors — Belsky, Avshalom Caspi, Terri E. Moffit, and Richie Poulton — hypothesize the existence of neurological and biochemical responses to environmental triggers. They also challenge those hypotheses.
The authors are data-driven psychologists who seek reliable insights from three longitudinal projects. One of them kept abreast of 1,000 New Zealanders from infancy to the present, beginning in the 1970s. Another observed 1,000 British twins with a focus on disadvantaged families. A third followed 1,300 children in various locales in the Unites States from birth to age 15. Carried out by the National Institute of Child Health and Development, the latter study was designed to investigate the day-care experience and has proved controversial. All three were First World studies with no pretensions to global application.
This wide-ranging book focuses on measurable adaptations viewed through a broad lens that shows just how much personality theory has ceded ground to the bedrock notion of temperament. A case in point: self-control in childhood is predictive, and the more of it children have, the better are their long-term mental and physical health prospects. These results are not surprising but they’re robust. Against the authors’ expectations, self-control proved to be a powerful predictor even after controlling for social class, IQ, and hyperactivity. Exactly how to enhance and improve it, though, whether by targeted early intervention or through environmental “nudges,” is less than clear. Bromides are not on offer.
As ever, attention-deficit/hyperactivity disorder (ADHD) perplexes researchers just as it does pediatricians and parents. After decades of work and truckloads of Ritalin, consensus would certainly be welcome. Wish again. The authors address the very current question of how and whether ADHD afflicts adults as well, albeit without assessing the possible effects of earlier treatment. Evidence for the persistence of a unitary disorder proves less compelling than one might expect. Some traces of distracted behavior tend to linger but an ADHD diagnosis is usually not a life sentence. This is encouraging.
A burning question of late: does parenting even matter much? The issue squirreled into psychology 20 years ago with such books as The Blank Slate and The Nurture Assumption, which downplayed nurture and emphasized genetics and biological predisposition. You can show that abusive parents harm their children psychologically, for example, but there are limits to “intergenerational transmission” of abuse. Parents may matter but so do peers. Moreover, it’s hard to factor in (or factor out) the degree to which hard-to-manage children affect how parents respond to them. Or how neighborhoods enter into the equation. The authors do make a valiant effort to dissect “the roots of competent parenting,” but it’s tricky terrain. Everybody favors warm and sensitive over unsparing and harsh — or do they? The authors find that “neighborhood disadvantage comes to foster antisocial behavior by first undermining supportive parenting.”
Several chapters address aspects of adolescent conflict. Most notably, Belsky is able to confirm his earlier hunch that childhood adversity and harsh parenting accelerate the onset of puberty. Adolescence in the wealthy Western world has come to mean that “girls and boys today end up with the bodies of adults while lacking adults’ social status,” leading to frustration on all sides. “What is it about Bad Boys?” ask the authors, referring to parents’ “helpless feeling” when their daughter falls for a teen who claims he can drive safely on four pints of dark beer. Perhaps unintentionally, the authors sometimes create an atmosphere of therapeutic pessimism — there’s simply not much parents can do, except avoid making things worse. In this section, they can do little besides buttress conventional wisdom and common sense: being bullied increases the danger of self-harm and is also linked to obesity; early adolescent use of marijuana is seriously dangerous but adult use is not very dangerous at all.
Problematic behavior, they stress, may arise in early childhood or originate first in adolescence, when it’s more likely to be a temporary snag than a sign of lifelong trouble. They test a theory put forth by one of them, Terrie Moffitt, that distinguishes between kids whose “anti-social” behavior can be detected as early as age two from those who begin falling afoul of parents, peers, and even themselves, or the law, in adolescence. The underlying assumption is that serious early onset misbehavior has a neurological basis and can prove “life-course persistent” while adolescent-onset problems can more readily be addressed. The authors describe longitudinal data that support the distinction, suggesting it should drive interventions. The wisdom that they’ll “grow out of it,” in other words, is misplaced when it comes to vicious young children; but adolescent-onset “snares” are most likely less worrisome.
The most controversial part of the book moves “Beyond the Family” to evaluate assumptions around day care. Longitudinal studies are well suited for such determinations, and the National Institutes of Health (NIH) project shows that $150,000,000 should buy good data. Belsky and his colleagues suggest, now with more evidence than in the past, that day care may be both useful and necessary but there can be too much of it. The NIH results confirm what attachment theory inferred long ago: day care at the expense of parent-child bonding may negatively affect development. And no matter how you measure it, a lot of high-quality pre-schooling won’t compensate for dubious parenting. Overall, the authors present an excellent case for the large-scale social benefits of extended paid parental leave. It would be helpful if the debate stopped there. It probably won’t.
The last third of the book focuses on genetics. The authors interrogate genome-wide studies and candidate genes to probe biochemical pathways that may affect self-control, interpersonal skills, and cognitive ability — all of which might in some brave and uncertain future be modifiable. Today, especially with respect to human development, the subtler interplay of genes and environment through phenotypes has displaced the anachronistic notion that DNA is destiny. So, for example, genomics can now be used to investigate the phenotypes related to smoking behavior (surprisingly subtle) and even to such broad concepts as “life success,” duly noting that life is unfair. Genome-wide studies make possible a “polygenic score” related to educational attainment that has relevance for social mobility. Some lone genes can have an outsize impact: the authors find that men who possess a single variant of a gene associated with anti-social behavior and are mistreated as children are far more likely to become violence-prone adults. (The gene in question codes for an enzyme that metabolizes neurotransmitters.) They find something similar with respect to depression, where negative life events pour the rocky ballast and a specific genetic variant lays down the tracks.
There’s less to say, as yet at least, about epigenetics, the emerging discipline that studies how environment may durably affect how genes behave. The authors looked at childhood victimization as it might affect later psychopathology, for example, focusing on the activity of various associated genes, but they essentially came up empty. Discoveries around what sorts of experience might turn specific genes up, down, or off await another day.
What The Origins of You does make abundantly clear is that psychology in the future must be genuinely multidisciplinary and able to capitalize on discoveries in genomics without being hamstrung by either biological or cultural determinism. On a more critical note, this book is sprawling in scope and the writing tends toward prolixity. Editorial guidance could have helped with the vast overuse of “adventure” as a descriptive or the strained metaphors about recipes. But the authors expect ordinary people to read the book “smorgasbord-like,” and that’s fair. Readers will readily see how, with assists from biology, it’s still true, as John Bowlby once said: “We do as we have been done by.”
John Galbraith Simmons is a novelist, a translator, and a science and medical writer.