Teenagers in love may be less likely to get mixed up in crime and substance abuse, according to new UC Davis research. But while romantic love seems to help keep teens law-abiding, casual sex can mean trouble.

Sociology professor Bill McCarthy and graduate student Teresa Casey found that teens in romantic sexual relationships had the same low rates of criminal behavior and substance abuse as celibate teens.

But when compared with their celibate peers, teens who had sex with nonromantic partners were up to 20 percent more likely to have been involved in criminal behavior — and as much as 58 percent more likely to have engaged in substance use.

“Romantic love may fill a void that occurs in adolescence between the weakening of parental control and the onset of a marital bond,” McCarthy and Casey wrote in their study. “Romantic love might discourage offending by strengthening adolescents’ social bond.”

The study, published in American Sociological Review, used advanced statistical techniques and data drawn from the nationally representative Adolescent Health Survey.