"Those born earlier perform better in school"—and according to a new study, it's because of the parents.
Moms and dads simply go easy on their later-born kids, according to data analyzed by economists V. Joseph Hotz and Juan Pantano, and as a result, first-born children tend to receive both the best parenting and the best grades.
The first thing to say about a study like this is that lots of readers will reflexively disagree with the assumption. With kids, as with anything, shouldn't practice make perfect? Don't parents get richer into their 30s and 40s, providing for better child-rearing resources? I'm a first child, myself, well-known within the family for being unorganized, forgetful, periodically disheveled, and persistently caught day-dreaming in the middle of conversations. For this reason, I've put stock in what you might call the First Pancake Theory of Parenting. In short: First pancakes tend to come out a little funny, and, well, so did I. And so do many first-borns.
But international surveys of birth orders and behavior (which might have offered me an empirical excuse to behave this way) aren't doing me any favors. First borns around the world, it turns out, have higher IQs, perform better in school, and are considered more accomplished by their parents. Looking at parent evaluations of children from the National Longitudinal Survey of Youth in 1979, the researchers found that mothers are much more likely to see their first children as high-achievers. They regard their subsequent children as considerably more average in their class (see table and chart below).