Laurie Kramer, a professor of applied family studies at the University of Illinois said parents are better at teaching the social niceties of more formal settings -- how to act in public, how not to embarrass oneself at the dinner table, for example. However, siblings are better role models of the more informal behaviors such as how to act at school or on the street or, perhaps most important, how to act cool around friends.
"Siblings are closer to the social environments that children find themselves in during the majority of their day, which is why it's important not to overlook the contributions that they make on who we end up being," Kramer says in a statement. "We know that having a positive relationship with siblings is related to a whole host of better outcomes for teenagers and adults."
The same holds true for other behaviors as well. For example, a female teen is at higher risk for getting pregnant if her older sister was a teenage mother, Kramer says.
Kramer and Katherine J. Conger of the University of California at Davis co-edited a volume on siblings for a recent issue of the journal New Directions for Child and Adolescent Development.