BALTIMORE (Map, News) - So what if your baby brother or sister “gets away with murder” — older siblings of the world are less likely to get in serious trouble because your parents “made an example” of you.

“Parents tend to penalize their oldest, first child most, and the younger child gets away with anything,” said sociologist Lingxin Hao of Johns Hopkins University. “This happens in many cultures.”

A new report by Hao, working with researchers at the University of Maryland and Duke University shows that in most cases, older children recognize their parents are likely to be tougher on them and typically get in less trouble because of this. On the other hand, parents’ vigilance seems to wane as younger children grow up, according to the article, published in the April 2008 issue of the Economic Journal.

Hao said she saw this principle at work in her own family and definitely exploited it as the youngest of three daughters. “For smaller things, I’m definitely wilder than my eldest sister.”

Her parents were consistent in holding all their children to a high standard. “It works in a way, because I knew what mattered and what didn’t matter,” Hao said.

The research team analyzed existing survey data from the U.S. Bureau of Labor Statistics’ National Longitudinal Study of Youth, which tracked more than 11,000 Americans for 16 years. They focused on whether parents kicked a child out of the house for getting pregnant or dropping out of high school, and whether parents withdrew financial support after age 18.

On average, having a younger sibling lowered the likelihood of an adolescent dropping out of high school by 3 percent.

This benefit increased if the family still had a child under age 18. For example, the probability of parents providing free room and board or financial support dropped 4.5 percent for an adult child who had dropped out of school, and 9.5 percent for an adult daughter who had a baby as a teen.

Their work shifts the emphasis of influence from peer pressure back to the parent, said University of Maryland sociologist Ginger Jin. “It also works better if the children are not always sure they know how their parents are going to react. There needs to be some uncertainty.”

khille@baltimoreexaminer.com