Twins don’t just do better in school than other kids, they are also less likely to get stuck in drugs and crime—according to a new study, which followed twins born between 1973 and 1982, done by the Centrum för forskning om ojämlikhet och hälsa (CHESS or Center for Health Equity Studies) at Karolinska Institute/Stockholm University. The study included 13,400 twins who had grown up together. The risk for a twin to be condemned for crime is 18 percent less than for a non-twin. The risk for a twin to get caught in a violent crime is 21 percent less than a non-twin. Twins also have a 21 percent lower chance of getting involved in drug-related crime.

“I imagine twins, since they are two, develop more empathy for others,” says pediatrician Anders Hjelm, who is one of the researchers behind the study. “Perhaps when it comes to drugs they are supporting each other and keeping tabs on each other.” Hjelm suggests that earlier research on twins has focused on negative factors. For instance, twins might be delayed when it comes to language and identity development since parents don’t have as much time to focus on them as individuals. “Now we have focused on the positives of being a twin,” he says. Twins aren’t more intelligent than other children, still they receive higher marks when they graduate from high school and are more likely to continue studying. “At school one can imagine they utilize four ears instead of two. They might help each other with school work and homework,” Hjelm continues. But it seems you only have help from your twin as long as you live close to each other. And few twin couples work at the same place later in life.