Does Birth Order Profoundly Affect Your Kids' Mental Health? The Findings Are Mixed
Every kid with siblings will claim that birth order affected them in some way or another: older children complain about being subjected to stricter rules, while younger siblings say their older counterparts hog the limelight. Older children may try to sway parents into giving them a larger portion of dessert, because they're "bigger." (Mind you, I may just be projecting my own sibling hang-ups here.) Petty squabbles aside, however, can birth order profoundly affect your kid's mental health? According to a handful of studies, whether your kid is the oldest, youngest, or smack in the middle can indeed affect a few aspects of their mental health.
One important thing to note, however, is that many of the studies regarding birth order suffer from one major flaw: they don't take family size into account. And, as Joshua Hartshorne, an assistant professor at Boston College's psychology department, explained in Scientific American,
There are many reasons that family size could affect our predilections and personalities. More children mean that parental resources (money, time and attention) have to be spread more thinly. Perhaps more telling, family size is associated with many important social factors, such as ethnicity, education and wealth. For example, wealthier, better-educated parents typically have fewer children. If astronauts are more likely to have well-educated, comfortable parents, then they are also more likely to come from a smaller family and thus are more likely to be a firstborn.