From the Washington Post:
Researchers at Ohio State University garnered little attention in February when they found that youngsters who lose their virginity earlier than their peers are more likely to become juvenile delinquents. So obvious and well established was the contribution of early sex to later delinquency that the idea was already part of the required curriculum for federal "abstinence only" programs.
There was just one problem: It is probably not true. Other things being equal, a more probing study has found, youngsters who have consensual sex in their early-teen or even preteen years are, if anything, less likely to engage in delinquent behavior later on.