Evolutionary Conflict and the Family

Let me be as blunt as possible, most of the beliefs you have about parents, and the socializing effects they have on children, are more wrong than you can possibly fathom. If you read my first installment on this topic, then the kickoff to this discussion sounds familiar. In fact, we’ve journeyed through the wilderness of parenting effects in three separate essays, now. Is there really a need for a fourth? I think there is, and the reason why is so that I can show you the absurdity lurking behind the idea that parental influences on children are large, prominent, and long lasting. The absurdity of it, in fact, is utterly staggering, stupefying, and as we will see, blazingly obvious once we pause and remember that humans, too, are a product of evolution.

When I read first read Matt Ridley’s book The Red Queen, I remember being shocked at the ideas he was proposing. In the book, Ridley promised to take the reader down a rabbit hole regarding how human nature evolved (and the role that sex played in that process), exploring shocking ideas. But there was a caveat; the entire premise was based on the idea that evolution actually happened, and that humans didn’t escape its grasp. The topic nature of that book and this essay are similar, and thus the same caveat applies. If you believe the Earth was created in 6 literal days, then we’ll have nearly nothing to say to one another. For those more tolerant of Darwin’s insights, the arguments presented here should have some traction. As you’ll see, a basic understanding of evolution imperils the assumption that parents wield great socializing power over their children.

We should start at the beginning, which is to say, conception. That magical moment when sperm meets egg holds an important insight. If you’re a mom or dad, do you know how much genetic material you contributed to your child? Times up, the answer is roughly 50 percent. Half from mom, half from dad, and basically there you have it: a newly developing human. It didn’t have to be this way, humans happen to reproduce sexually, but that’s not the only way to skin a cat. We could simply clone ourselves, in which case we would share 100 percent of our DNA with our offspring. But this wasn’t in the cards for us, we’re sexually reproducing creatures, and that means we combine our genes to make our kids (it really is quite freaky if you pause long enough to think about it).

There are two inter-twined consequences of this. First, the fact that parents and children share genetic material could completely explain why parents partly resemble children — not just in appearance, but also in temperament and personality. And in fact, this is essentially what a deluge of twin studies on personality and temperament have shown. The shared genetic overlap of parents and children seems to do just fine in explaining the similarity that exists between them. More on this in a moment, but let’s first discuss that second consequence of sexual reproduction. We assume that the interests of parents and children are perfectly aligned and that they’re harmonious. Any glowing father in the delivery room would surely attest to their willingness to die for their child. That’s fine, and I wouldn’t doubt it, but the very fact that we reproduce sexually virtually guarantees, not harmony in the family, but conflict.

The insight comes to us from one of the greatest living biologists, Robert Trivers. An entire essay could be devoted to his insights, because they are in fact lengthy, brilliant, and essential to evolutionary theory. Yet, I’ll limit myself to only one at this point: parent-offspring conflict. You’re not a clone of your parents, you have your own desires and interests, and as an infant especially, your desires tend to trump everyone else’s (such as when it’s 2:00 AM and you’re hungry). It really can’t be all that difficult to fathom, can it? As the psychologist Steven Pinker reminds us in How the Mind Works, the desires of mom, dad, and the kiddoes’ can often be at odds (not always of course, but sometimes). Your head would spin if you knew how deep this conflict ran and how early it starts. Consider the following from How the Mind Works (p.442 & 443):

Parent-offspring conflict begins in the womb. A woman with an unborn child seems like a vision of harmony and nurturance, but beneath the glow a mighty battle goes on inside her. The fetus tries to mine the mother’s body for nutrients at the expense of her ability to bear future children. The mother is a conservationist, trying to keep her body in reserve for posterity. The human placenta is a tissue of the fetus that invades the mother’s body and taps into her bloodstream. Through it the fetus secretes a hormone that ties up maternal insulin, increasing the levels of blood sugar, which it can then skim off. But the resulting diabetes compromises the mother’s health, and over evolutionary time she has fought back by secreting more insulin, which prompted the fetus to secrete more of the hormone that ties up insulin, and so on, until the hormones reached a thousand times their usual concentration. The biologist David Haig, who first noticed prenatal parent-offspring conflict, remarks that the raised hormone levels are like raised voices: a sign of conflict. In a similar tug-of-war, the fetus increases the mother’s blood pressure, forcing more nutrients its way at the expense of her health.

Post pregnancy, you guessed it, more conflict. Mom and Dad want some “alone time”, but why would that matter to their five year old? Want to watch the conflict ramp up? Have another child, and presto-chango, now there are two children who are half genetically related to each other, and thus, also have conflicting wants, needs, and desires. At this point, the conflict is flying around the room hot and heavy and Dad retreats to the garage in search of something that needs to be repaired.

The point has nothing to do with whether or not parents love their kids, they do (there are evolutionary reasons to care for kin too, obviously). The point is that we have this illusion of complete harmony, when we shouldn’t. The insight, by the way, applies to marriages. We imagine that couples, when they are at their healthiest, should be conflict free, but there is no evolutionary reason to suspect that either (for more on this I would highly recommend David Buss’s The Evolution of Desire). Two adults have conflicting needs, sex drives may not align, ideas about finances may not match up, anyone in a relationship longer than a month knows that it’s not all rainbows and kittens. Kittens grow up, and when they do (if they’re anything like ours) they shred the curtains and vomit at randomly determined locations throughout the house (it doesn’t mean you get rid of them, of course, they’re just not as cute as they used to be). The long and short of it is that parents and their children (as well as parents themselves) have conflict wired in to their interactions, by virtue of how we reproduce.

On to the brass tacks, why should the conflict between parents and children matter much for the absurdity of parenting effects? Let’s first zoom in on what we actually mean when we say “parenting effects.” What most people mean, whether they realize it or not, is “socialization” effects. So the real question is this: once you account for the fact that parents and children share genes, do parents then also socialize children in a manner that lasts for life and spills over outside of the home? The answer is not really, not as much as you’d think. How do we know this, we know it in part from a legion of twin studies that fail to find a shared environmental effect (this is where parental socialization would largely emerge, if it were having a huge effect). Thus, the similarity between parents and children can largely be explained by the fact that they have genetic overlap and not much more.

Children are clearly socialized, though. Right? Of course they are, the question simply becomes who does the socializing? As I’ve written about before, the brilliant psychologist Judith Rich Harris makes a compelling case that the socialization of children that really matters happens outside the home, and with almost near exclusivity in the peer group. Remember, children in many cases have conflicting desires with their parents. They desire to fit in with their peer group; moreover, they have to fit in with their peer group to some extent. Mom and Dad are great, but there are no mates to be found at home, and being able to navigate social situations at school, and on the playground (and anywhere else peers are encountered), is essential to functioning prosocially in the real world. When your heart first starts to flutter at the thought of holding hands with someone, or sitting by them at lunch, or whatever, the worst way to go about that is to fail miserably at fitting into the social milieu that you find yourself in. As Harris also illustrates, there is more than one way to be successful in a group (be funny, be smart, be whatever an open niche in the group [and your genes] will permit you to be), but you have to be successful in that group. Mom and Dad likely want you to be well behaved, thoughtful, and well mannered. But if being boisterous, stupid, and risky is what gets you that girl’s phone number, which one do you think will win out? Like I said, conflict.

There’s a more tangible way to see socialization effects in progress, and it’s with language. This is not an instance where I’ve stumbled on some fantastic example all on my own, folks like Steven Pinker and Judith Harris have used it previously, but it’s just so useful that we’ll conscript it into service again. You may know someone who was the child of immigrants. Assuming that your acquaintance was born here, and their parents born in another country (and raised there), you’ll likely notice some interesting qualities. First, the accents of your friend and their parents are likely very different. Your friend sounds like you, not really so much like their parents. They might even speak their native language at home, but nonetheless they speak with the same accent as you most of the time. This is no new phenomenon to language scholars who noted long ago that young children adopt the accent and dialect of their environment. After reaching a certain age, accents do not tend to change and it becomes harder to learn a new language as we get older. Thus, their parents who recently immigrated retain their native accents. Yet their children adopt the accent of their peers. Why?

Accent and language (the language that we speak, that is) are environmentally shaped; completely environmentally shaped. Thus, they represent a perfect avenue for studying socialization. If parents were the prime movers in the socialization game, then their children should presumably adopt their accent, their dialect, and their way of speaking. But this isn’t what happens. Children, as Harris notes, have to fit within their peer groups. Their reproductive success long term depends on it. Parents may have every desire in the world to shape, mold, and remake their children in their own image. But tough luck, children have their own interests to look out for, they have their own ideas about the world, and as they age, these become more and more apparent. Your influence as a parent was had when sperm met egg. Your child will be socialized, rest assured of that much, but it just won’t be you that does much of it. If we had bothered to read a little more Trivers and a little less Freud or Spock (and much less of some archaic holy text), we might have expected as much.

Twin studies represent a wasteland for the idea that parental socialization effects are the most important socialization effects out there. And evolutionary theory suggests that we never really should have anticipated them in the first place. What continues to amaze me is the tendency for people to read articles like this one and conclude that I’ve said one of two things: 1) that parents are unimportant and can treat their children ever how they like, and 2) that genes are all that matter for personality. If you think either of those is true, then you’re just not trying very hard to listen. Parents clearly matter, for a whole host of reasons, but that does not also mean that they are the primary socializers of children. Second, the environment clearly matters. As Pinker and Harris hammer home to us, children get socialized, they have a culture, and in many ways it’s different than that of their parents. They have to fit in their culture, and you have to fit in yours as a parent. Sometimes they overlap (such as when parents and children share interest in sporting teams), other times they’re different.

To assume that parents could or should be the primary socializing force in a child’s life betrays an ignorance of a century or more of advances in evolutionary theory and behavior genetics. It’s also arrogant, because you reflexively refuse to consider that you might be incorrect about your assumptions. Parental socialization does not represent a natural law. A mature understanding about parenting has to include more than just what is written about in parenting books and spouted out by pop psychologists. It means understanding the whole picture, the evolutionary picture. In that framework, there wasn’t a huge reason to suspect ahead of time that parental socialization was some sort of leviathan. Moving forward, there is no reason to persist in the idea that parenting is all, or even most, of what matters for the socialization of children.


Brian Boutwell is an Associate Professor of Criminology and Criminal Justice at Saint Louis University. Follow him on Twitter: @fsnole1

Filed under: Genetics


Brian Boutwell is an Associate Professor of Criminology and Criminal Justice at Saint Louis University. His research interests include the biological evolution of human traits, genetic and environmental underpinnings of human violence, and general intelligence. His published articles have appeared in PLOS One, Behavior Genetics, Developmental Psychology, Journal of Psychiatric Research, Criminology, and Social Science and Medicine as well as others. He was also a coeditor of The Nurture versus Biosocial Debate in Criminology: On the Origins of Criminal Behavior and Criminality (Sage).


  1. Sarka says

    Much of this seems like common sense to me rather than a staggering breakthrough brought about by evolutionary science. E.g. that parents and children can have conflicting interests and not some natural ideal harmony, and that peer group is at different stages important, and even more important in some ways than parents…There is also the non-peer world beyond parents too. Any ideas of natural harmony of interests, and of course of the overwhelming importance of relationship to parents for the whole socialisation process, seem to me not age-old errors of people unenlightened by evolutionary thinking so much as aspects of rather recent ideologies, some associated with always contentious modern psychological theories.
    Not that one should go to the opposite extreme. Given social set-ups in which children spend a lot of time with one or both parents (that’s not evolution, it’s culture), they will usually – being extremely imitative creatures – acquire a lot of basic habits and attitudes and social strategies as well as mannerisms from parents (and no doubt a strong genetic component in personality and aptitudes just reinforces this tendency), and parental tastes and views will get projected into the sort of sub-peer groups they tend to choose….(school is not just one “peer group” – it’s an environment in which children to some extent gravitate to social subgroups, and they don’t do it randomly!)

  2. Children are clearly socialized, though. Right? Of course they are, the question simply becomes who does the socializing? As I’ve written about before, the brilliant psychologist Judith Rich Harris makes a compelling case that the socialization of children that really matters happens outside the home, and with almost near exclusivity in the peer group.

    Whoa – I was worried that’s where you were going with this.

    There’s no evidence for Harris’s theory. Sure, there are clear peer effects on language, but language is far and away from personality or from how much money you end up making.

    Most of the examples she uses in her books are just as genetically confounded as standard family research. Indeed, the research coming out of the Add Health data is showing that peer similarities are genetically confounded, just like parent-child similarities are.

    1) that parents are unimportant and can treat their children ever how they like, and 2) that genes are all that matter for personality. If you think either of those is true, then you’re just not trying very hard to listen. Parents clearly matter, for a whole host of reasons, but that does not also mean that they are the primary socializers of children. Second, the environment clearly matters.


    Unfortunately, Pinker and Harris, in tearing down the Blank Slate, invented a form of “half-slatism” in its place: genes matter and parents don’t do much, but the “environment” still matters as well, so half-slatism goes. This is despite the fact that all the evidence is pointing against this idea.

    After all, if peer groups mattered, peer effects would also show up in the shared environment. After all, parents select their children’s peer groups by their choice of where to live. But neighborhood effects are found to be absent.

    Perhaps instead of the idea of peer socialization, there’s an even simpler idea that fits with all the evidence: environment – and by this I mean “socialization” specifically – doesn’t alter personality much at all. “Environment” matters in the sense that we see some generational changes in people, but much of that could just people reacting to the broad environment they’re in now. Particularly, people could be reacting to new possibilities afforded by technological change.

    Good piece otherwise. At this point, readers should be on the page that humans are animals that are products of evolution like all other life on Earth, and hence all the qualities humans possess were crafted by Darwinian forces one or another.

    • You mean when they apply statistical witchery that takes the randomization out of the study, they can make it look like moving had an effect when in fact had no effect at all.

      • What do you mean? According to everything I’ve read about MTO, the reason that earlier results showed no effects was that the effects only showed up in people who moved as children, and those people hadn’t reached adulthood when the earlier results were published, so they weren’t included in the sample back then.

        The New York Times article also mentions that the “natural experiments” of comparing public housing residents whose buildings were demolished (and they received housing vouchers because of this) with those whose buildings were not demolished also show significant neighborhood effects.

        Do you have any evidence to back up your assertion that the researchers employed “statistical witchery”?

  3. I’m curious who these people are saying families are harmonious. Whole ‘breakthrough’ seems premised on straw man. Worse- you can leave out DNA entirely. If you cloned yourself and popped the fetus in the womb (or grew him to any age you can imagine) there still would be conflict. This isn’t because of genetic differences, its because we are individuals with individual minds. If you want to talk about why we aren’t bees, well we still dont understand bees very well, so there’s not much light there either.

  4. You have a good point that we shouldn’t expect a child’s parental socialization to shape how they act around their peers because of how different parent-child and peer relationships are. But what about their relationships with other authority figures? It seems likely that many people would use their interactions with their parents as a model for how they interact with teachers, bosses, police officers, etc.

    • jim nichols says

      Relationship to Authority is more birth order effect than anything else, which does place it in the realm of family influence rather than peer pressure.

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  6. Tamara says

    Anecdotes are anecdotes, but I take issue with the concept of parenting falling within the shared environment. My experience is that siblings raised in the same households actually experience entirely different environments which is in contrast to what it assumed in these twin studies.

    My own experience, two daughters aged 8 and 3.

    First 4 years in totally different communities, play centers homes etc.
    My eldest spent her first 2 years with her father (at home) working nights while I worked days; whereas I spent the first year with my 2nd daughter while her father worked.
    Entirely different parental employment and income situations across time.
    2nd daughter got whooping cough at 2 weeks of age and nearly died. This massively changed how my partner and I parented her (i.e. much more anxious, worried and cautious), and these differences continue (despite our attempts otherwise).
    Obviously the environments in the womb were totally different in terms of maternal stressors, likely some differences in nutrition etc.
    I got mild PND with the first child but not the second.
    Our 3 yr old will go to a different primary school than the 8 year old does.
    My partner has changed careers, so my youngest daughter will know her dad as a psychologist rather than as a musician.
    Our youngest visited her first developing country at 1 year of age, my eldest at age 6.

    These are just some of the differences. I could literally write for about an hour on the differences.

  7. Santoculto says

    The way humans experienced the world is individually unique but we have a genotypical basis of behavioral operationality that define how we are experience uniquely the mysterious and fantastic act to live. We no born only with a “plan a” to the x or y environment but with a limited range of possibilities to interact and to respond to this everyday challenges. If we born in sub-optimum environment for long time all of us will develop “plan b” strategies to survive in this unwelcoming reality and based on out own possibilities.

    The idea that humans are so lack of instinct during their first decades of life that they are bizarrely passive for every environmental action must go, and this is confounding immature brain responses as well other things with “omnipresent environment make me do it”. Always it’s a relation of two, we and our “environment, since our positive reciprocity to the climate type to the fit-ness of our personalities/temperaments or intelligence types and levels to the environment we are living.

    Just like a rock we can be very resistent/ resilient to the any environment, diversely avg or more sensitive, and of course the environmental pressure also have their impact but the last answer is always of the being and not the environment. Whatever how force you are using against a rock only a rock resistance/durability level that will determine if it will be broke or stay solid.

    So even a inanimate entity define your destiny (at least in your very un personal milieu) why not human beings???

    To say genetics is our basis to behave is not exactly a nightmare of behavioral determinism as most of this people on the blank believe but the sign of individual emancipation that we have or can have our own tricks and that environment is not that big brother who force us to behave based on your humor sense.

    Genetic basis limite us beyond our own limits or boundaries of potentialities but not what we can do within our boundaries (wisdom).

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