Moffitt 2011: What Childhood Self-Control Predicted by Age 32

Does childhood self-control predict how your adult life goes? Yes, across a whole population and with a clear gradient, but the prediction is about groups, not about any one child. In the Dunedin cohort (Moffitt et al., PNAS, 2011), 43% of the children in the lowest fifth for self-control had a criminal conviction by age 32, against 13% in the highest fifth. Even in that lowest fifth, 57% had none.

Both halves of that sentence matter if you have been wondering why you are not achieving what you planned, so this post keeps them together.

What did the Dunedin study actually follow?

The cohort is 1,037 babies born in Dunedin, New Zealand, in 1972 and 1973. The team behind the paper, led by Terrie Moffitt and Avshalom Caspi, kept in touch with 96% of them to age 32. Self-control came from a composite of nine measures taken between ages 3 and 11 (observers, parents, teachers and the children themselves).

I read the open-access version in PubMed Central (PMC3041102), including the tables. Everything below is from that text unless I say it is my own arithmetic.

How big are the differences between the top and bottom fifth?

The paper reports outcomes at 32 for the most and least self-controlled fifths of the cohort. The last column is my own calculation from those percentages.

Outcome at age 32	Highest fifth	Lowest fifth	Ratio (author’s calculation)
Multiple health problems	11%	27%	2.5 times
Polysubstance dependence	3%	10%	3.3 times
Annual income under NZ$20,000	10%	32%	3.2 times
Children raised in single-parent homes	26%	58%	2.2 times
Criminal conviction	13%	43%	3.3 times

Two readings are available, and both are accurate. The ratios are large: low self-control children were roughly two to three times as likely to land in each category. But the lowest fifth was a long way from uniform doom. Seventy-three percent of them had no cluster of health problems, and 68% were not on a low income. The curve is a tilt, not a cliff.

The tilt also ran through the middle of the distribution. When the authors dropped the least-controlled fifth, or both extremes, the linear association survived. That is what the word “gradient” in the title means: a child at the 60th percentile fared a little better on average than one at the 40th, not only a child at the 95th compared with one at the 5th.

Is it just IQ and family background?

Self-control in this cohort overlapped with both: r = 0.44 with IQ and r = 0.25 with family social class. The authors ran each outcome twice, first plainly and then with those two controls added. For criminal conviction the odds ratio went from 1.83 to 1.71. For the physical health index the incident-rate ratio went from 1.196 to 1.111. Some wealth measures shrank much more: the standardized effect on socioeconomic status fell from -0.263 to -0.082.

The fair summary is that self-control carried independent weight on every outcome, and a smaller share of the wealth story than the raw gradient suggests. Intelligence and class background are not nothing.

What happened to the siblings?

A natural worry about any cohort result is that families differ in ways nobody measured. Moffitt’s team used a second sample for that: the E-Risk study of 2,232 British twins born in 1994 and 1995. They took 509 same-sex fraternal pairs, rated each child’s self-control at age 5, and looked at outcomes at 12. Within the same family, the twin with lower self-control smoked more (B = 0.07), did worse at school (B = -0.13) and showed more antisocial behaviour (B = 0.09). The school and antisocial gaps held after adjusting for the twins’ IQ difference.

The limit is built into the design. These children were 12, not 32, and smoking and school marks are early signs, not adult wealth or health. The sibling data shows the pattern is not only a family-background artifact. It cannot show the adult gap directly.

Where do people go wrong along the way?

Moffitt’s group also tracked what they called snares in adolescence: starting to smoke by 15, leaving school without qualifications, and becoming a teen parent. Low self-control predicted each one (odds ratios of 1.69, 2.28 and 1.79). Each extra snare went with more adult problems.

Controlling for snares reduced the self-control effect by a lot on some outcomes: 63% for substance dependence, 61% for single-parent child rearing and 42% for crime, against 29% for income. The direct effect stayed significant for nearly everything. This is the paper’s most useful detail for anyone reading it as a life guide, because snares are events, and events sit downstream of choices that someone else, or a different setup, can sometimes alter.

Can self-control change in adulthood?

The paper included a small analysis of people who became more self-controlled between childhood and young adulthood. Their age-32 outcomes were better than their childhood scores alone predicted, even after controlling for where they started. The childhood and young-adult measures correlated at only r = 0.30, so a lot of people move.

I could only read this analysis in the main text. The detailed outcome numbers sit in a supplementary table I did not reach, so I have no effect size to report. The authors themselves caution that natural change in a cohort is not the same as change produced by an intervention.

For intervention evidence, the closest thing I reached is a 2016 update in the Journal of Experimental Criminology by Piquero, Jennings, Farrington, Diamond and Reingle Gonzalez. Its abstract says seven studies were added to an earlier database of 34 randomized trials of programs for improving self-control in young children, and that the authors judge these programs effective for improving self-control and reducing delinquency. I read only the abstract, not the effect sizes. A related line of evidence, Hofmann and colleagues’ beeper study, suggests why training alone may not be the whole story: people high in trait self-control reported weaker desires and less conflict rather than more resisting.

How early does the signal show up?

Earlier than most people expect, though weakly. Ratings made by trained observers at ages 3 and 5, before any teacher or parent had formed a view, still predicted health, wealth and convictions at 32. The effect sizes were modest, the paper says. A three-year-old’s score is a faint pencil mark. The composite across nine measures and eight years is what produces the table above, which is a reason to distrust any quick test, quiz or app score that claims to read your self-control in a minute.

The cohort-wide conviction rate gives another useful anchor: 24% of the whole sample had one by 32. The lowest fifth, at 43%, sat well above that, and the highest fifth, at 13%, well below. Self-control sorted people around an average that was itself already high.

Is the same gradient visible in adult careers?

Daly, Delaney, Egan and Baumeister (Psychological Science, 2015) looked at work instead of crime. Across two British cohorts they found that each standard deviation of teacher-rated self-control at 7 to 11 went with a 1.4 percentage-point lower chance of being unemployed, after adjusting for intelligence, social class and gender. The effect is small per person and visible only across thousands of lives. The FAQ below gives the sample and the caveats.

What does the study not establish?

• It is observational. Nobody assigned children to low or high self-control, so the paper cannot say that raising a child’s score would, by itself, raise their income at 32.
• It is two Western samples. Dunedin is one city, and the 1970s cohort grew up under a welfare state and labour market that no longer exist.
• Its main measure is a composite built from other people’s ratings of a child. That is a different thing from a lab willpower task, and from whatever you feel at 6:30 on a Tuesday.
• A 2018 replication of Mischel’s marshmallow test found that the wait-time link to later outcomes weakened once family background was controlled. Dunedin used far richer measurement and controlled for IQ and class, but it is a reminder that self-control correlations tend to shrink under heavier controls.
• I did not verify a 2016 Nature Human Behaviour paper that was suggested as a follow-up, so nothing here rests on it.

What does this mean if you are 35 and stuck?

Average gradients describe populations. If you are 35 and stuck, the Dunedin tables say your childhood rating shifted the odds, and that is all they say. The paper reports no outcome that was fixed at age 5.

Adult behaviour also depends heavily on setting. Wendy Wood and colleagues’ studies showed that when students moved universities, habits tied to the old place stopped firing. If the people who fare better are those who rely less on in-the-moment resistance, arranging mornings, rooms and commitments so that effort is not needed at the weak moment is a reasonable response to the data.

One place where an outside witness changes the stakes is waking up: with DontSnooze, a missed 30-second video check-in sends a random camera-roll photo to your friends, so getting up does not hinge on how disciplined you feel at that moment.

Which parts of the Dunedin data are worth acting on?

Three things stand out for an adult reading this as a planning document. First, the snares result: the paper’s biggest drop in the self-control effect came when smoking, dropping out and early parenthood were held constant, so the stretch between 12 and 20 mattered a great deal and adult decisions can still be steered away from comparable traps (a payday loan, a lapsed course, a job left without a plan). Second, the changers: scores moved, and movers fared better. Third, the sibling pairs: two children from one household, raised the same way, still diverged. Nobody in the data was a prisoner of their address.

Self-control also fails in a predictable shape when a small reward is close, as Ainslie’s pigeons showed, and the time of day you try to exercise it matters too, per the parole-ruling data.

A quick way to use the numbers

Take the 27% versus 11% health gap. It is 16 percentage points (my own subtraction). Spread across 100 people from each end of the distribution, that is 16 more people with multiple health problems, and 73 of the 100 low self-control people with none. Planning around a gradient means treating it as odds you can shift at the margin, which is where snares, settings and habits sit, and not as a verdict about your character.

Sources reached: Moffitt et al. 2011 (PMC full text), Daly et al. 2015 (PMC full text), and the abstract of Piquero et al. 2016 (OJP page). Not reached: the PNAS publisher page (403), the paper’s supplementary tables.