It’s in Our Genes. So What?

DNA takes you only so far.

The pioneering genetics company deCODE and the child-development lab at the University of California, Davis, would seem to have little in common, given that the latter is full of adorable moppets who can barely walk and the former is run by a towering geneticist, Kari Stefansson, who always reminds me of a Viking. More than six feet tall, Icelandic, with steely eyes that make you think he's on the verge of conquering, if not pillaging, he built the company into a powerhouse, discovering scores of DNA variants linked to important human diseases.

Coincidentally, the week that deCODE Genetics, Inc., filed for bankruptcy in November, a fascinating study of those UC children appeared. The company's troubles raise questions about the value of linking complex diseases to genes. The study makes me wonder if we have been attributing to DNA a power in determining intelligence and other complex traits that it doesn't deserve.

Over the past decade, deCODE has discovered genes linked to type 2 diabetes, atrial fibrillation, heart attack, prostate cancer, glaucoma, breast cancer … seemingly every ill ever visited upon humanity short of boils. But that wasn't good enough. The gene variants, it turns out, account for only a small fraction of the risk of developing these diseases. Plus, many genes affect that risk. As a result, tests for disease-risk genes, and even drugs that target the pathways the genes affect, aren't all that informative or useful, limiting the market for both diagnostics and treatments based on disease genes. Based in Reykjavik, deCODE is trying to sell the scientific arm of the company; maybe future discoveries will prove of greater medical benefit.

A more pointed rebuke to DNA centrism comes from research on how children's behavior affects how adults treat them. That kids (through their behavior) create their own environment, so to speak, has been known to science since the 1960s (and to parents forever). But scientists have hardly studied it, notes psychologist Claire Vallotton of Michigan State University, in part because they have been loath to look too hard into something that implies a baby is to blame for how she is treated.

The few studies that have been done find that parents respond less, and less quickly, to fussy, crying babies. They're less affectionate to homely babies. They don't read and speak as much to fidgety, difficult babies. They respond more to infants who make complex pairings of gestures and words than to those who simply point ("Daddy's chair" vs. just "chair"). How much babies gesture, smile, make eye contact, and babble affects how adults respond to them, including responses that shape how verbal a child will be, how emotionally secure she will feel, and thus what kind of adult relationships she will have. It isn't just parents. "Children's temperament also influences how teachers treat them at least as early as first grade," says Vallotton. "That has ramifications for later academic success."

To investigate how babies' behavior elicits certain adult behavior, she filmed at the UC child lab, where caregivers use "baby signing," gestures that reinforce babies' babbling. What she found, as she reports in Infant Behavior & Development, is that the more children (ages 4 to 19 months) respond to caregivers' signs and gestures with signs of their own or by pointing or waving, the more engaged and responsive caregivers were, responding by getting down on the floor, making more eye contact, or talking more with the child.

This is a small study, and we shouldn't make too much of it. But one has to wonder. Research has linked genes to intelligence, social skills, neuroticism, risk taking, impulsivity, and more. In most cases, "linked" means determining that the behavior is partly inherited, but not how the gene brings about the behavior. What if the gene affects a trait known to be strongly heritable, such as appearance or temperament, and what if that trait in turn elicits particular behaviors from parents and teachers: behaviors such as responsiveness, paying attention to, interacting with, speaking to—things that affect how a child turns out academically and socially?

If so, we are mistakenly attributing these outcomes to genes "for" intelligence and the rest, when in fact all the genes do is give a child looks or temperament that elicits, for instance, IQ-boosting responses from adults. That's important for the obvious reason that adults, armed with this knowledge, can learn to treat all children—not just the cuties who so easily bring out the best in us—in a way that nurtures their hearts and minds to develop to their fullest.