Does your kid have an internal locus of control? If so, it's a good thing because kids who have one by age 10 are less likely to be overweight at age 30. They also grow up to be healthier adults and are less likely to describe their health as poor or show high levels of psychological stress. Despite childhood IQ, education, and family income, these tendencies remain.

A locus of control is the extent to which people think they can influence events through their own actions. Each of us has one. It's a natural component of a person's personality and is shaped by childhood experiences and interaction with parents. Those who are shaped to believe they are in charge of their lives have an "internal" locus of control. Those who are not have an "external" locus.

"I think it is quite probable that a major explanation why children with a more internal locus of control behave more healthily as adults is that they have greater confidence in their ability to influence outcomes through their own actions," says Dr. Catharine R. Gale, of the University of Southampton in the UK. They may also have higher self-esteem, which can encourage healthy habits.

If you're a mommy or daddy, think about this message from Dr. Gale: "Parents who encourage independence and help children learn the connection between their actions and consequences tend to have children with a more internal locus of control."