*The following is excerpted from an online article from Healthday.
Boys and girls who are unruly and aggressive from a young age were found to be more likely to start having sex before age 16, researchers reported in the February issue of the journal Pediatrics.
The Australian study also found that boys -- but not girls -- who are socially anxious or withdrawn also tended to begin sex at a younger age.
Such behavior problems in boys as young as 5 and in girls as young as 10 can be used to accurately predict early initiation of sex, the researchers said.
These results show that, for some kids, parents may need to begin discussing sex at an earlier age to help their children make the right decisions, said Dr. Cora Breuner, a pediatrician at Seattle Children's Hospital and a member of the American Academy of Pediatrics' committee on adolescence.
"That may be earlier than people are comfortable with. That's kindergarten. But you can't talk about this stuff early enough," said Breuner, who was not involved with the study. "There are certain kids that should be targeted with whatever intervention is needed to prevent early sexual activity."
The new report is based on a long-term study of nearly 2,900 Australian children born in 1989.
Certain behavior patterns at younger ages -- particularly what the researchers called "externalizing" or "internalizing" behaviors -- appeared to indicate which kids were likely to have sex earlier than 16.
Externalizing" behavior problems include aggressive and delinquent actions, while "internalizing" behaviors include social anxiety and withdrawal.
Boys who were acting out by ages 5 and 8 proved twice as likely to have sex at an early age. Girls who were disruptive at ages 10 and 14 were more than twice as likely, the study found.
But the findings showed that boys showing signs of internalizing behavior at age 10 were two and a half times more likely to have sex before 16.
"Those are the ones that really surprised me, these kids who we don't pay attention to because they aren't causing problems," Breuner said.
"They don't know how to interact with other kids and they don't know how to say no, or they feel like the only way to be accepted by their peers is to say 'yes,' " Breuner said.