Is There a Single Biggest Predictor of a Person's Success? A: Yes


What is it that determines personality? Our future health, wealth, and happiness? Why do some people endure such hardships physically, emotionally, and economically, while others lead a relatively well-adjusted, healthy, and happy existence?

These are questions which fascinate Clinical Psychologist Professor Richie Poulton. Poulton spent decades observing people everywhere from kindergartens to maximum security prisons. To answer these questions, you must take a large group of people, and measure their life experiences in a great deal of detail, so that you get a comprehensive picture of the range of human experience, to better understand what makes us who we are.

Photo: PortraitsbySam
Photo: PortraitsbySam

In 1972, a medical school from a small city in New Zealand embarked on the ultimate nature/nature test. They decided to take every child born in the city that year and follow them for life. For 40 years scientists probed every aspect of their existence - their medical history, job history, habits, personality, genes, sexual activities, criminal offences, relationships, successes, failures... everything. Nothing was off limits. All information was guaranteed to be held entirely confidential, and is one of the reasons for the study's success. Decades later, over 96% of the participants still continue to take part; a remarkable rate, when with most studies there is less than a 50% take-up rate. (One of the secrets of the success of the study, is that participants are flown back, if necessary, for further testing, and for those who are unable to travel or are institutionalized in prison, the study experts come to them.)

The experiment is called The Dunedin Longitudinal Study, and its subjects are now the 1037 most studied people in the world, and the richest source of information on what really makes us who we are. It is highly-lauded and internationally recognized. There is no other significant study in the world which has accumulated the same level of data, including even undesirable behaviours, the way that the Dunedin has.

Results from this study can predict how children are going to turn out as adults. Typical longitudinal studies measure just a couple of metrics. What's special about the Dunedin Longitudinal is that it measured almost every aspect of human behaviour and development, resulting in a complete picture of a human life. From the study of these 1037 people came an avalanche of findings. 1500 papers, over 40 years, have been published in many scientific journals around the world.

Photo: Lisa Holloway, Chicken Peek-a-Boo
Photo: Lisa Holloway, 'Chicken Peek-a-Boo'

Early criticisms to the study centred around the idea that conclusions made about one town in New Zealand couldn't possibly apply to the rest of the world. This often also included a stereotype of New Zealanders. To check and account for this, aspects of the study were then repeated in the suburbs of inner city Pittsburgh... with similar results. The findings demonstrated that there are fundamental truths driving behaviour, regardless of nationality, economic, or ethnic background.

Some Findings:

* Cesarean births and left-handedness have no lasting effects.

* Thumb-sucking and bed-wetting are passing phases with no psychological significance.

* Children who slept the least during their early years become the most overweight adults. They also have poorer cognitive function during adolescence, and anxiety problems in their 20s.

* The more TV people watched as children, the more likely they were as adults to have unhealthy cholesterol levels and be cigarette smokers. The amount of TV watching also predicted how they would later do in university and whether they would end up getting a degree. Children who watched the most TV were 3X more likely to leave school without any qualifications. Those who watched the least were 4X more likely to graduate with a university degree, irrespective of IQ or family income.

Key Findings:

The Dunedin study found that children can be classified into 1 of 5 basic personality types, and these early character types persist into adult life. It identified these traits in preschooler children, showing that our temperament at 3 is our temperament at 23.

They are:

Well-Adjusted: Active; organized; reasonably adaptable; quite social; flexible; resourceful; fit in well socially; make up ~ 40% of the population.

Confident: Go-getters; entrepreneurs; not afraid to take on challenges; a love of thrill-seeking; not necessarily the life of the party but are people with a presence; ~ 28% of the population.

Reserved: Somewhat timid, but not to the point of being paralyzed by it; quiet; a natural tendency to set back, watch, and observe; ~ 15% of the population.

Inhibited: An adult whose shyness tends to interfere with their ability to do very simple things; they have a hard time leaving home and establishing a life for themselves; fearful, anxious, neurotic; closed to experiences; high-strung; don't like novelty; prone to develop depression; Ex: Japan's Hikikomori; ~7% of the population.

Undercontrolled: Grow up to be high-strung, irritable, easily fly off the handle; closed to new experiences; do not like novelty; do not like change in their environment; involved in antisocial activities; have a much harder time adjusting to work lives and prone to long bouts of unemployment; impulsive, prone to hostility, rage, uncontrolled anger, and losing composure; more likely to develop heart diseases, diabetes, lung problems, STDs; ~10% of the population.

The Confident, Reserved, and Well-Adjusted personality types are generally productive members of society. Their mix of mostly positive traits means they tend to do well in life. They're more likely to be happily married, have friends, successful careers, and enjoy better health.

Published in 1963, this book is considered groundbreaking for its honest treatment of children’s emotions, especially anger.
Published in 1963, this book is considered groundbreaking for its honest treatment of children’s emotions, especially anger.

The Inhibited and Undercontrolled personality types tend to create a great deal of trouble and angst, both for themselves, and for the rest of the community. Lifelong negative outcomes are predicted.

Is There a Single Biggest Predictor of a Person's Success?

Is there anything in childhood that predicts who will be successful and who won't?

Yes, there is one trait, in particular, that can be measured in 4 yr olds that forecasts one's later economic, job, status, health, and relationship success. Answer: Self-control.

In almost every measure of success, self-control made a huge difference. High self-control children, as early as age 3-5, became adults who owned their own homes, were business entrepreneurs, had solid jobs, started saving for retirement, and were considered good money managers by their friends who knew them well. Whereas children exhibiting poor self-control became adults who had issues with debt, had their possessions repossessed, bankruptcy problems, and tended to be known as poor money managers by their friends. But the problems are not just financial. Low self-control also produces a range of health problems from obesity, heart disease, high blood pressure and cholesterol, and STDs. They are also more likely to be addicted to tobacco, alcohol, and drugs. Low self-control has high costs.

Are you in command of yourself, or is yourself in command of you? Some people think that they did not choose to explode, "it just happened", while others may feel the same irritation or anger, yet can down-regulate and control it.

One of the best-known demonstrations of self-control is the Marshmallow Test of Stanford University, first conducted in the 1960s. 4 yr olds were placed in a room with a marshmallow, and given a simple choice. Eat the marshmallow now, or hold back for 15 min and receive two. It is a simple but illuminating test of constraining one's impulses.

What promotes self-control?

Warm, balanced, sensitive and responsive parenting beginning in infancy; being firm and consistent in discipline; having peers who have self-regulating behaviour who enforce norms of social behaviour which exhibit control and regulation.

The Good News

The good news is that self-control is not fixed. With dedication, it can be improved. It is a lot harder to change the person than to change what the person does. But by trying to alter behaviour, you can change how the world responds to that person. It doesn't mean it changes the person's personality, but it does change the punishment-reward system the person experiences with certain behaviours.

The Dunedin study found there is something we can teach any child, any person, no matter what their personality type, self-control that can increase their future health, wealth, and happiness. All people benefit from better self-control skills; even those with average control can have an improved life from improving their regulation. These traits are not set in stone. However it also proved that many adult problems begin much earlier in life than previously imagined. The early years are seminal in all sorts of ways, and early intervention is the best predictor of altering one's path for good, but it is never too late to make changes to one's behaviour and improve the chance of happiness and success.


Transposed from the documentary 'Predict My Future: The Science of Us' (2016)

Is There a Single Biggest Predictor of a Person's Success? A: Yes
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  • pikuroy

    In our culture, enlightened Yogis have always talked about three great powers of human beings and have always advised training kids to develop these three qualities. The difference between a highly successful man and a loser are these three qualities.

    1. Power of focus:- how much a person can block distraction, withdraw from unimportant things and focus on the job.

    2. Power of decision:- will power. Take a decision and stick to it no matter how difficult the situation gets.

    3. Power of unselfishness:- anyone can work hard for himself. Anyone can give something as transaction. But how much can he give without expectation?

    Like 3 People
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  • Grond21

    That is fascinating. And I suspected it would be self-control as the single biggest predictor of success. Just because I'm familiar with the marshmallow test. But to hear it explain like this is truly incredible! Thank you very much Amanda. I enjoyed reading this a lot

    Like 2 People
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What Girls & Guys Said

  • OlderAndWiser

    Excellent explanation of an interesting study. Very well written!

    LikeDisagree 2 People
  • sailaway

    The definition of success is super subjective and is currently holistically defined based on how society is set up currently. These findings are more conclusions drawn on how well a population can fit into and work under the current system- a system that no longer works for the majority of the working-class population.

    Disagree 1 Person
    • AmandaYVR

      Success is not subjective. It was defined appropriately - physical health, cognitive health, total lifespan, lack of chemical dependencies, incarcerations and illegal activities, educational accreditations, financial stability, asset ownership, job satisfaction, relationships longevity, etc etc.
      You're conflating the socioeconomic problems of today's society with individual achievement. This is not about conformity and fitting a square peg into a round hole. These markers are primarily about stability, not status.

    • sailaway

      Individual achievement is correlated with society's systemic issues over history- it's not what's happening today, it's trauma over generations. You even stated it yourself, "owned their own homes, were business entrepreneurs, had solid jobs, started saving for retirement" - those are completely dependent on expectations and socio-economic politics of a country. Many people don't own homes particularly in younger generations, that's not a marker of success and neither is having a solid job or being a business entrepreneur. Those are predominantly outcomes of our capitalist economic model where basic human rights have been privatised to a point where we can't afford many of these things. Some families can't even afford fruit and vegetables to get the nutrients they need- and putting the key fault on an individual's lack of 'self-control' is surface-level victim-blaming of the underlying issue of poor governance.

      I come from New Zealand, the racial discrimination on generations of trauma in indigenous communities in towns that are predominantly white colonial settlements is a major issue and one that continues to marginalise the lower socio-economic families who get stuck in a system where they have not been supported and actively discriminated upon. I wouldn't base your conclusions on one research paper done in the 20th century in a country where racism and disparity are still prevalent to this day.

    • AmandaYVR

      Yes, agree with you on the existence of systemic racial discrimination that does impact society and individuals.
      But as I said, they repeated the study in inner city Pittsburgh, a very economically depressed area... and had similar results. The main difference was that there were more homicides, because of the higher gun ownership rate in the U. S.
      This is not "surface level victim-blaming..."

  • Smoothing

    At first when I saw the title of your "my take", I was sceptical of the credibility of any answer that I might see.

    Looking at the parameters for the research, I was inclined to see the credibility in the whole process.

    The conclusion is also admittedly good though somewhat lacking because such research is is limited to the unpredictable variation in the ever changing human social dynamics based on the overall ultimate balance of nature.

    There can never be a precise predictor of factors underlying individual human achievement. Though, how easy or how hard it can be for an individual to achieve a particular goal can most certainly be recognised.

    The factors that affect a human being's life at any point in time are numerous at any given time. If it was ever possible to be precise, even events like the outcome of an election would be predictable precisely. Since the same statistical technique is employed in both cases of research.

    We can only do our best. That is nature. Beyond that we just have to let it be.

    Like 1 Person
  • Spade07

    The answer is Self- discipline and the ability to create or change habits... aka self control. I figured this out myself but honestly you can go on youtube and Search Jim Rohn and he will tell you the same. So will 100 other millionaires. So will Andrew Carnegie who has been saying it since 1908!!! So did Ancient Kemet thousands of years ago. But in my opinion this isn't the secret to success or even close to it but that is a whole other topic.

    To me what promotes it should be one answer: Knowledge and understanding. If you know neurologically how to create and change habits that is everything. Also having a chief aim in life and a motive that is strong.
    I'm not pulling my answers from theorist either who studied the topic like scientist and then gave a conclusion. I'm telling you what millionaires tell me. One of which was the richest man when he was alive. But Yes parents can set their kid up to where they dont need this knowledge because they built there kid into a successful person. But the only problem there ever is in the world in Ignorance. That's what my 86 year old mentor says and when you think about it, it makes 100% sense. For instance race issues... The truth is there is no such thing as race. It have been proven by science and history already. If we remove these labels and truly BELIEVE in our subjective minds (emotional mind/ subconscious mind) that this is no such thing as race, it would rid of many bad things. One race= human race. That's just one example.

    I wanna say I loved this and I did but at the same time the answer was obviously to me the whole time and should be to anyone who just takes the time to think. But I'm glad you posted this because you gave the people reading this so much value. More than they could ever know.

    But anyone who has tried or trying to do something great in there lives knows this. I'm not talking about the people who do everything right and live some boring life that from the outside looks like success because they got lucky to form the right habits young. I mean the people who grow into something they never though they could. I'm on the front line of it in my own life and I've studied success all of 2020 in quarantine and the things I found were shocking but all seem to lead back to self- discipline because if you dont have it the rest is worthless except for 1 thing but you get my point and understand why. There was 1 thing that I will say is more important than self discipline but you cannot use it without self discipline lol.

    As far as the personality thing I fit in 3 of them. The only thing I read that shocked me was "Children who slept the least during their early years become the most overweight adults. They also have poorer cognitive function during adolescence, and anxiety problems in their 20s." This describes my friend to a T. She is very overweight and has a lot of anxiety but I don't know if she slept a lot as a kid or not.

    LikeDisagree 2 People
  • lonelyfortune

    Objective success is the most overrated thing in our modern society. Subjective success is all that counts in your own life. There is no need to measure yourself by how society looks on you. It only means that you're measuring yourself by how well you imitation others? Why do you need to be like others when you're trying to find to yourself?

    Like 1 Person
    • AmandaYVR

      Yes, it shouldn't really be about the trappings of life, the big ticket items and such. But success could just as easily, or more appropriately, be defined as stability - mental, physical, emotional, financial.
      The surest way to discontentment is comparison to others. But in order to have a stable and reasonable contented life, you do have to exercise planning and self-control.

    • What you mean is resilience. A resilient person doesn't need stability in their life to feel content. With the right mindset, you can have all the emotional, financial, and mental drama in your life, it won't keep you from going on. Stability is an illusion, you see, because control is an illusion. Things happen how they happen regardless of how hard we try. The only thing that matters is that we keep going forward and don't get stuck in the past.

    • AmandaYVR

      Ok, fair enough. But I do think it's a combination of all that.
      Some things you can prepare and plan for (rewards and dangers), and other things, there was absolutely nothing you could have done to see it coming, or prevent it, and with that, you just have to try and ride the wave, not let it engulf you.

  • Abtraction

    what a load of crap (I have read this garbage before, years ago), as if one point in time at age 4 determines your future. It's as if people thinking school grades are a factor in success. I'm sure many people know someone from school who had good grades, but never amounted to anything significant.

    It's determination and hard work, typically people who work non-stop and never give up.

    Sometimes, just luck.

    There's also, who determines success? If your goal was just to have 2.5 kids that made it to college, and you did it. Or send a rocket to the moon. Not everyone wants to send a rocket to the moon, some people are content to have a roof over their heads, some have hopes to change the world.

    Some people just don't have the same level of determination or passion. I have entire tablets filled with ideas in the working. Just not enough time or resources after 8-10 hours of coding for the corporate overloads to execute them all.

    I have a firm belief that all the solutions to society & tech exist in the heads of a few people, that never get tested because they are too busy flipping burgers or writing code for a computer security firm, both of which I have done...

    LikeDisagree 4 People
  • CapitalismFailed

    So your personality is fixed at the age of 3 but you can change it any time? Frankly I'm confused and sceptical. It's an interesting study, but like most interesting studies it doesn't tell us anything useful.

    Like 1 Person
  • Floppy2112

    Self control? I sense everybody is going to want to be too PC to admit the main trait correlated with success, IQ. As it stands that adds up to about 25% of success. Other things like competitiveness, openness, likability, cooperation all do play a role. But if you want to use a single factor to predict success, it's IQ. Self control is downstream from that.
    If you asshole is tight from that, relax it is only 25%. 75% is determined by other things, including sheer luck. And loads of smart people are losers too.
    The better idea is not try to boil it down to one thing. I would say take into account 3 things.
    It also depends on what you call success. Defining that is more mutabal than what it takes to get 'there'. If it's financial, then we know what that looks like. But if you consider victory in life having a wife and kids and live a decent lifestyle, that's okay too. IQ still correlates heavily to that kind of success too. It would be nice to be able to have the conversation without having to be lynched by the woke cult. But hey, we can sneak nuggets of non-PC info out every once in a while.

    • AmandaYVR

      Nope, it's not IQ. Your a layman thinking that. The study disproves this theory.
      It's self-control.
      Success is well-defined. It's not subjective here.

    • AmandaYVR

      * you're a layman

    • lol... wow.
      You can't make this shit up...

  • zeitgeist057

    Thanks for the great read! It doesn't give much hope to those who want to change their fate though, being "... our temperament at 3 is our temperament at 23...". If you have poor self-control and/or irrational, antisocial behavior, you are going to be the same at 23 as 3, and presumably just an older version of that at 73 as well.

    It's also interesting such a high percentage of the population is maladaptive. It rings true, since out in public you hardly see a day go by without some kind of negative interaction taking place between people.

    Like 1 Person
    • AmandaYVR

      Thank you. 🙏
      Yes, in my city, out walking on the streets, those maladaptives sure do squawk a lot. (Some must have Tourettes 😉 )

      Yes, I hear you. In some moments, I had the same thought. It would feel like a rubber stamp on your forehead, perhaps, to be diagnosed as such. But I did some more reading and here is some hope:

      "The most important thing to remember about “The Dunedin Study” and the reason we here at “The Forever Years” love it, is that it investigates nurture as well as nature and results show that nurture has an important part to play in whether those children with “Undercontrolled” or “Inhibited” personality types go on to have “positive life outcomes” or not. Personality traits can overlap. Nurture can “push” children from “functional” to “non-functional” personality types and vice versa. For example, a “Reserved” child who isn’t adequately socialised could become “Inhibited”. An “Inhibited” child, with the right supports in place, can be “drawn out” to become “Reserved”.

      Findings from “The Dunedin Study” show conclusively that for some individuals, multiple problems tend to aggregate. A portion of children on the study who manifested the “Undercontrolled” or “Inhibited” personality types had these in combination with delays in significant areas such as speech and language acquisition and in taking their first steps. For a portion of them (interestingly, these children were predominantly male) learning to read was also a great struggle. This in turn led to a dislike of school, leaving school early and, following on from this, a high incidence of involvement in criminal activity. “Something as innocent as delayed speech then, if not dealt with early, can gather force over the course of a lifetime,” says “The Dunedin Study” Associate Director, Dr. Terrie Moffit.

    • AmandaYVR

      Director Professor Richie Poulton says knowing now (because of study results) that some kids have a much higher chance, for example, of ending up in trouble with the law, can provide an opportunity to avert negative life outcomes by creating individually tailored intervention plans. Such things as significant learning delays, poverty, childhood abuse or neglect, witnessing domestic violence, substances consumed by a child’s pregnant mother whilst he or she is still in the womb, an absence of attachment, structure, boundaries, positive encouragement or correct professional intervention for particular significant issues, invariably lead towards “negative life outcomes” when combined with particular personality types.

      Children who come into the world, then, with “Undercontrolled” or “Inhibited” personality types could be described as “guns loaded by Nature”. But it is Nurture, meaning the presence or absence of certain positive or negative factors, that determines whether or not the “triggers” of these guns are pulled. “Nurture” and “early positive intervention” are our hope. The childhood years are indeed, when we look at the set personalities that we are born with, “The Forever Years”, as these personalities persist into adult life. The outcomes don’t need to be negative, however, if “at risk” personality types are parented accordingly and if we teach our children “Self Control”, an all important trait which is learned, rather than fixed..."

      Just in case you want more info, this was a pretty good write-up: (no pressure to read though)

  • Obscurite

    A bird in the hand is worth two in the bush and psychiatrists are notorious even to children for being liars. The children who nommed the first treat blindly were less intelligent than those who waited but the most intelligent children ate the first and ransacked his desk for the rest and you never knew they existed.

    Also this is dumb. The greatest common indicator of a child's success is their parents.

    Like 1 Person
  • Nice intake. But i beg to differ. There is no guarantee for success. U can have all the resources and keys of success. Then one incident change all of that. A car accident lets say, traumatic brain injury and the person ends up in a wheel chair.
    There are also many factors, some people no matter how life bring them down they still shine. And others despite being pampered become criminals (see the story of Oscar Pistorius)
    so its very relative

    • AmandaYVR

      Of course. There are no guarantees in life. Not even to success. The study finds there is, however, a greatest predictor.

    • Definitely there is always a predictor. But whether or not the circumstances allows that to happen is the key.

  • Boodica

    I immediately thought of the marshmallow test. This is far more information on an age old question. Change is possible but only with yourself. You can not change anyone else. So do what is necessary to retrain your own brain.

    Like 1 Person
  • KingdomForAKiss

    Great writing, Amanda! As always. Very interesting study!

    Like 1 Person
  • Jjpayne

    Wow! That is a very interesting study with a very interesting conclusion! That self control can dramatically effect our lives. it's an interesting idea to be sure 🤔

    Like 1 Person
  • Avicenna

    Very interesting, thanks. Did they control for ADD/ADHD?

    Like 1 Person
    • AmandaYVR

      It was not mentioned in what I saw, but I'm sure they took it into account. The study was very thorough.

  • humanearth

    What I read there makes a lot of sense. I did notice something in myself when reading this.

    What I saw in myself was the major change in my traits. When I left one life to start another life.

    I am not just talking about job change. I'm talking about a complete life and mindset change. (Honesty I think the change saved my life

    If you see me now. I am no where near the same person. That I was just 20 years ago.

  • LoveIsFake

    FALSE!! I watched a lot of tv as a kid and I don't smoke or have high cholesterol. I'm the only fit one in my family and the healthiest 😂 I also would sleep veary little and I'm not fat, I'm lean. Plus I even graduated high school and am getting a degree in marketing. So I don't think lack of sleep, and tv watching will make a person prone to being fat, a smoker or uneducated. I'v done all those things as a kid and I'm the opposite of what they described I'd be.

  • Juxtapose

    "Some people think that they did not choose to explode, "it just happened", while others may feel the same irritation or anger, yet can down-regulate and control it."

    I've been trying to tell that to others but they keep making excuses.

    Disagree 1 Person
  • ecfresh

    Nice explanation. How about the 4 year old who trips the person holding the mushroom bag to get all the mushrooms? We have all seen that 4 year old.

    • AmandaYVR

      Uh... what? This image you have described makes me smile and I even laughed too... but I really have no idea what you're talking about here. Please explain. The suspense is killing me 😃

    • ecfresh

      Oops. It was meant as a joke and I’m happy you laughed but I didn’t mean to use the word mushroom. Bag of marshmallows was the intent.

    • AmandaYVR

      Aaaaaah that explains it! Feel better now, my brain can stop trying to solve the puzzle.

  • AlexanderAnttila

    For Christians the answer is simple. Trust in the Lord with all thine heart and lean not to your own understanding, and He shall make your paths straight.

    Disagree 2 People
    • See but doing that stuff usually takes a hell of a lot of self-control.

      The difference for the Christian is just the definition of "success," which could be different for anyone. Self-control is still one of the biggest factors in achieving that success.

    • @RP_Blackburn The difference is that we do not have to trust in our own strength alone. "I can do all things through Christ who strengthens me."

    • No, not only our own strength, but of course God doesn't want us to be weak? If he has given us a spirit of power and love, after all. And we are to be like Jesus, and can you think of anyone more self-controlled than him? But his self-control wasn't his goal, it was (along with relationship with God, yes,) how he could accomplish the goal where humans failed to (resisting temptation, submission to God's will).

      Self-control is a cardinal virtue in Christianity. God provides guidance and grace, but we are to be virtuous and grow in our relationship with him. There is more to following Christ than self-control, but there is also more to it than trust. And even if you trust, you may lack the self-control to act on and only on that trust.

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