Every social phenomenon has its scientific moment, when people reach for neuroscience, genetics, or psychology to make sense of it. In Abigail Tucker’s new book, Mom Genes, motherhood is on the docket. Drawing on studies from all three disciplines, Ms. Tucker tries to grasp what makes mothers tick, across the mammalian kingdom, from pregnancy on, while also trying to explain why mothers vary so widely, not just from mammal to mammal, but, for example, from American mother to French mother to Chinese mother. Ms. Tucker wants to “have it all.” She wants to know it all.

The book fails to deliver. Part of the problem is the writing. Personal stories of Ms. Tucker mothering her four children comprise almost half the book. Such stories are fine when trying to illustrate broader points, yet her stories are written in such a way as to be of little interest to anyone who is not a mother, especially a millennial mother, and a fairly self-absorbed one at that. The reader learns of the author’s fondness for “a bottomless mimosa brunch,” until the moment she learns “that babies suddenly trump brunch;” how the author spent her first moments away from her baby on the very day a small earthquake hit, and she was “where else?—in the changing room of Ann Taylor at the time;” how the author’s husband is “a celebrated lunch-box chef whose diaper-changing arts border on origami.” I found Ms. Tucker’s over-reliance on metaphor and punchy verbs, and her affected and stagy witticisms, tiresome, although I do recognize that people in other demographic groups might think otherwise.  

The bigger problem is her obsession with scientific studies and an almost naïve respect for them, as if any investigation that uses the scientific method deserves our respect and attention. That almost forty percent of the results yielded by psychology studies have been shown not to be reproducible, violating a basic tenet of science, fails to give her pause. If a scientific study has been done on a question that interests her, she cites it authoritatively.

Nor does she seem to appreciate the difference between causation and association or bother to offer some qualifying statement on the matter when citing a scientific study. For example, she mentions a study that says identical twin sisters, who have a common genome, are more similar as mothers than regular sisters are, while adopted sisters are on average less similar than biological sisters in their mothering style. Having established in the reader’s mind the genetic causal link, the author (naturally) sums up matters with a cute saying: “‘Mirror, mirror, on the wall, I am my mother after all.’” Yet the causal link is not so obvious. Maybe the link is just an association. Maybe twins are mothered in the same way—held by their mothers at the same moment, fed at the same moment, given identical clothes to wear, and even addressed in the same tone of voice because their parents can’t tell them apart—and this explains why twins mother similarly. At the other end of the spectrum, maybe adopted children are mothered differently compared to biological children because mothers look upon them differently, which is why adopted children, in turn, mother differently when they grow up. Perhaps it is nurture, not nature. There may be a genetic link to mothering or there may be no link at all.

Eight pages later, Ms. Tucker cites another scientist who admits that motherhood’s origins may indeed transcend genetics, with “many things working together, interacting with so many other things.” This is infuriating. The reader thinks, “But you just said . . .” Such bait-and-switch goes on throughout the book on topics ranging from breastfeeding to mother’s sleep to post-partum depression. By the book’s end the reader doesn’t know what to think about the origins of motherhood.

Instead of being a well-argued book with a clear thesis, the book’s narrative can best be described as “stream of consciousness” sprinkled with studies. The topics covered in the book move about the way thoughts and feelings pass randomly through the mind of the narrator. The difference between this book and, say, a novel by Virginia Woolf, is the occasional appeal to science in the author’s interior monologue.   

The Science of Everything

More interesting is why people cling to science to explain social phenomena in the first place, especially when science cannot readily do so, or declare anything more than, “On the one hand, this; but on the other hand, that,” as too many variables exist for the scientific method to conduct valid experiments on these matters. In the past, people lived comfortably without knowing what made mothers tick. They just went about the business of life the best they could. Then again, people have always wanted to understand the origins of things, or at least understand the force that moves things. That elemental drive may be operative here.

In another place and in another time, religion served that explanatory purpose, sometimes taking the form of “It’s God’s will,” or, to use a more superstitious version, “‘Tis the devil made it happen.” There were other explanations available to people, especially among the uneducated. If a mother attacked her baby in a fit of post-partum rage—Ms. Tucker discusses this issue, noting how in the mammalian world the first born is statistically the most vulnerable to attack—an uneducated person might have said that the mother struck her baby because she raised her fist and brought it down on the baby’s head. Another uneducated person might have maintained that the cause of the attack lay in the mother’s angry words being shouted into the air at the same time as she hit her baby.    

In any event, religion devised a complete explanation. A religious person’s contention for why things happened was irrefutable. In the case of the superstitious man who believed in the devil, refuting him would have required someone to prove to him that there was no devil.

The religious explanation rested on people believing they were subject to the will of some deity and being led by that deity toward some predetermined end.  Religious people studied events as a manifestation of that deity’s power. Modern secular people, because they no longer believed in a deity, looked within humanity for the causes that create power and move things. Yet instead of overthrowing the religious paradigm, they simply tweaked it. Rather than believe in a deity that guided events, they believed in individuals, or groups of individuals, that guided events. Rather than believe themselves to be moving toward a deity’s predetermined goal, they believed themselves to be moving toward a goal set by individuals or nations.

Thus, history became the next subject to try to understand the force that moves things. Certain historical events caused other events, historians claimed. The problem arose when trying to decide which events were actually causative. There were so many to choose from, indeed, an infinite number. Did Napoleon lose the Battle of Waterloo because one of his aides caught a cold and delayed delivering Napoleon’s message to attack? Or was it Napoleon’s moral failings that led to the loss? Or perhaps no individual was responsible; instead, larger historical forces, perhaps the collective will of the French army, or the collective will of the working class, led to defeat. If the French army’s collective will was at fault, did Napoleon play any role at all, and, if so, was the French army’s will always transferred to Napoleon, affecting his will and decisions, or just sometimes? Rather than help people understand why events occurred, historians often confused people even more.

The same illogic dogs the historical explanation for why a mother attacked her baby. Was it because the au pair called in late that day? Was it because the mother had a bad day at work? Was it because the mother didn’t work? History fails to consistently explain why people mother the way they do. The power that moves mothers remains unknown. At least the uneducated peasant, who would have said, “The devil made the mother attack her baby,” was being consistent, and with about the same likelihood of being right as the historians. 

Social science came next as a means to explain social phenomena. Whether in sociology, anthropology, political science, or economics, social scientists applied the scientific method to events to tease out their origins. In the case of a mother attacking her baby, an economist might say that an increase in the price of gas is associated with such attacks; a political scientist might blame racism or sexism; a sociologist might correlate such attacks with a lack of mental health services in the neighborhood. Yet social science proved no better than history at offering definitive explanations for events. In some ways it proved worse, for it presumed to be science and used the scientific method, and therefore put a straitjacket on how one was allowed to think about such events.

The scientific method works well in astronomy, where few variables exist, as the celestial bodies are so far away that no other variables can be found and factored into a scientific study, even if the astronomers wanted to do so. In matters of everyday life, however, there exist an infinite number of variables that demand to be accounted for. This prevents a serious social science experiment from ever being conducted. Nevertheless, social scientists purposely exclude those variables to conduct their experiments, thereby adopting a stance of willful ignorance, while calling what they do science. At least the uneducated peasant’s ignorance was not willful.

In our time, we use “real science,” most often neuroscience and genetics, to explain events. This is the animating spirit behind Ms. Tucker’s efforts to explain motherhood. One study she cites says that a “tug-of-war” goes on between a mother’s and father’s genes inside the baby’s placenta, with the father’s genes often winning out, thereby explaining the child’s subsequent behavior. Another study she cites says the quality of care that a mother gives depends on her mid-pregnancy ratios of progesterone and estrogen. A third study says exposure to oxytocin somehow sensitizes a mother’s neurons to a baby’s cries. Yet none of these studies is definitive or predictive in any reliable way, a point that Ms. Tucker eventually gets around to admitting—after the reader has been lulled into believing otherwise. The studies demonstrate curious associations without evidence of causation.

As explanatory devices, neuroscience and genetics have an advantage over social science. The former can ignore the whole world of “nurture,” meaning the world of social interactions, and focus solely on nature, meaning the brain and DNA. The number of variables that need to be considered shrinks dramatically. Yet nurture is inevitably part of the equation, as Ms. Tucker admits, rendering any scientific explanation for motherhood incomplete.

Indeed, the neuroscientists are hardly better than the uneducated peasant on this front. Just as the peasant reached for the devil to explain social events—the devil was the peasant’s all-around, go-to explanation for any kind of dark behavior—so do today’s neuroscientists and their lay believers invoke the “hypothalamus” and the “amygdala” whenever the mystery of bad behavior arises. Neuroscientists know little about these brain organs other than that they somehow play a role in behavior, but whenever inexplicable behavior does arise, these organs are invariably invoked to explain it. Somewhere inside them lay the motive force for events, we are told. Not surprisingly, these organs make an appearance in Ms. Tucker’s book, although they possess about as much real explanatory power as the devil.   

Why do people look to science to explain the motive force behind events and behavior? Perhaps to guide policy. But because science’s explanations are so incomplete and purposely ignore so many variables, they cannot reliably do so. Not surprisingly, at the book’s end, Ms. Tucker’s solutions for helping mothers include the usual catch-all solutions pushed by progressives for any malady: fighting racism, lessening inequality, and expanding government. Conservative policy boilerplate, such as lower taxes and more access to charter schools, is no better, as nothing in the science of motherhood dictates these solutions either. All of these policies are simply the preferred solutions of partisans more generally. They stem from ideology, not science. Nothing in the science of motherhood drives them.

Instead, people probably look to science to explain social events and behavior because it is in their nature to do so, in part because they’re curious; in part because they want to give someone or some thing moral responsibility—that is, they want to blame; and in part because they want to know whether something was fated, thereby rendering judgment on the relative power of their own wills.

The peasant had the devil to explain why mothers are the way they are. We have science. On the matter of motherhood’s origins, neither one is really any better than the other.