Simon Moore, one of the researchers, explains the results:
Intrigued by this association, Moore turned to the British Cohort Study, a long-term survey of 17,000 people born during a one-week period in April 1970. That study included periodic evaluations of many different aspects of the growing children's lives, such as what they ate, certain health measures and socioeconomic status. Moore plumbed the data for information on kids' diet and their later behavior: at age 10, the children were asked how much candy they consumed, and at age 34, they were questioned about whether they had been convicted of a crime. Moore's analysis suggests a correlation: 69% of people who had been convicted of a violent act by age 34 reported eating candy almost every day as youngsters; 42% of people who had not been arrested for violent behavior reported the same. 'Initially we thought this [effect] was probably due to something else," says Moore. "So we tried to control for parental permissiveness, economic status, whether the kids were urban or rural. But the result remained. We couldn't get rid of it.'
Of course, as well educated (and presumably low candy consuming) individuals, we learned long ago that correlation does not imply causation. Nonetheless, Mr. Moore believes there is a rationale behind the results:
‘The key message is that this study really raises more questions than answers,’ says Moore. One of those questions is whether sweets themselves contain compounds that promote antisocial and aggressive behavior, or whether the excessive eating of sweets represents a lack of discipline in childhood that translates to poor impulse control in adulthood. Moore is leaning toward the latter. It's possible that children who are given sweets too frequently never learn how to delay gratification - that is, they never develop enough patience to wait for things they want, leading to impulsivity in adulthood. It's also possible that children who are poorly behaved from the start tend to get more candy.