And those with the least self-control at age three are more likely to drop out of school, break the law and struggle financially, the study authors concluded.
Researchers analysed data on about 1,000 children born in New Zealand in 1972-1973 and tracked them until age 32. Their self-control was measured at various points starting at age three using assessments by teachers, parents and the children themselves.
Children with high IQs raised in socio-economically advantaged families tended to have greater self-control, according to the study published in the Proceedings of the National Academy of Sciences.
But even after accounting for intelligence and social class, children who had more self-control at age three went on to earn more money and have better health at age 32.
Children need self-control
Children with less self-control were more likely to adopt negative behaviours - to get pregnant as a teenager, to smoke, to become a single parent and to be unemployed.
Three-year-olds with little self-control were also more likely to have financial difficulties and poorer health in adulthood. Medical exams and blood tests showed they had more gum disease and sexually transmitted diseases; were more likely to be overweight, have high cholesterol or high blood pressure and signs of inflammation; and were more likely to be addicted to cigarettes, alcohol and harder drugs.
"Self-control is vital for scanning the horizon to be prepared for what might happen to you, for planning ahead to get where you want to go, for getting along with other people and attracting their help and support, and for waiting for the really good things that are worth waiting for, instead of jumping for short-term fun," said lead study author Terrie Moffitt, a professor of psychology and neuroscience at Duke University.
"We all use it every day, but some of us use it in a more skillful way than others."
The researchers found a similar link between self-control at age five and later success. Using data on 500 pairs of fraternal twins in Britain, they found that the sibling with lower self-control scores at age five was more likely to smoke, perform poorly in school and engage in antisocial behaviours at age 12.
What is self-control in children?
"Whether one is from a rich family or a poor family makes a difference, no doubt about it. If we are endowed with intelligence and talent, that makes a difference, no doubt about it," said Jay Belsky, a professor of human development at the University of California, Davis, who was not involved in the research.
"But what also matters is our own self-generated behaviour, the extent to which we regulate or manage our impulses, and the choices and decisions we make. We are active agents who pilot the plane that we fly through life."
If you've had a child fling herself on the ground because you said it was time to leave the playground, or wail and kick as you try to wrestle him into the bathtub, you may ask: does that count as poor self-control?
Perhaps, though only if it happens frequently and in many situations, the researchers noted.
Poor self-control was described as having a low tolerance for frustration, lack of persistence in reaching goals, difficulty sticking with a task, impulsivity, over-activity and restlessness, and difficulty taking turns.
"A three-year-old with good self-control can focus on a puzzle or game and stick with it until he solves it, take turns working on the puzzle nicely with another child, and get satisfaction from solving it, with a big smile," Moffitt said. "A child with poor self-control might refuse to play with anything that required any effort of him, might leave the puzzle in the middle to run around the room, might lose his temper and throw the puzzle at the other child, and might end up crying or fussing, instead of feeling satisfied."
The good news is that self-control can be taught, said Alex Piquero, a professor of criminology at Florida State University.
According to the research, children who improved their self-control as they aged fared better in adulthood than their scores would have predicted.
"There is a lot of research that shows there is effective training parents and teachers can do in the first 10 years of life that improve kids' self-control," Piquero said. "If we can identify these deficits early, they can improve their self-control and we won't have the negative outcomes."
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