Getting Away With It by Raina Kelley FROM Newsweek

It's considered a "fact" of sibling relations: the baby of the family always gets away with murder. If the oldest brother had a curfew of 11 p.m. on weekends, his baby sister just has to call if she's staying out all night. But can it be proven that parents are always stricter with their first born?

Researchers from the University of Maryland, Duke University and The Johns Hopkins University say yes, if there are younger siblings in the family, out of concern for the example that is being set for them. Using economic game theory, which is the use of mathematical analysis to determine what kinds of choices people make, the research team looked at more than 11,000 subjects in the National Longitudinal Study of Youth to predict levels of parental discipline. They also discovered that having one additional younger brother or sister can lower the chance that an adolescent will drop out of high school by 3 percentage points. Researchers also found that though parents are much less likely to financially support or put up with a rebellious teen if there are still younger children at home, their resolve weakens as older siblings move out and younger siblings grow up. "As a result, the theory predicts that last-born and only children, knowing that they can get away with much more than their older brothers and sisters, are, on average, more likely to engage in risky behaviors," says University of Maryland economist Ginger Jin, one of three coauthors of the study.