In April 1972, doctors in the small New Zealand city of Dunedin began enrolling every baby born at the maternity hospital into what would become one of the longest-running health studies in the world. More than 50 years later, it’s still going. According to ‘The Dunedin Multidisciplinary Health and Development Study: overview of the first 40 years, with an eye to the future’ published by the study's own directors in the journal Social Psychiatry and Psychiatric Epidemiology, the Dunedin Multidisciplinary Health and Development Study has followed 1,037 people from birth, with day-long checkups at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26, 32 and, most recently, 38.
For that last assessment, in 2010-2012, 95% of surviving participants showed a retention rate researchers themselves say is unusually high for this sort of long-term study. The authors also note that the study’s repeated measures across childhood, adolescence, and adulthood have made it a model for testing how early-life factors shape later health and behavior.
For American millennials and Gen Z, who had grown up listening to endless and often contradictory advice about willpower, trauma, and self-improvement, the Dunedin findings offer something rarer: decades of genuine data on actual people, rather than theories. That’s what the research says, and why it matters for how you think about your own habits and history.
Self-control in early childhood turned out to matter more than expected
One of the study’s most famous findings was tracking how well the children managed frustration, impulsivity, and persistence, beginning when they were toddlers. The study, ‘A gradient of childhood self-control predicts health, wealth, and public safety,’ published in the Proceedings of the National Academy of Sciences found that kids who scored lower in self-control as young children were more likely to have worse physical health, more substance dependence and weaker personal finances by age 32 than those who scored higher, even when the researchers controlled for differences in intelligence and family social class.
Importantly, this wasn’t true for low-end kids only. The same PNAS study found the pattern to hold as a gradient across the entire range of self-control scores, meaning even modest differences in childhood self-regulation were associated with modestly different adult outcomes.
