Having siblings is pretty great. But it can also mean a lifetime of rivalry and trying to one-up each other. If you have siblings or have more than one child, then you know this! There are also some preconceived notions about birth order and how it pertains to what kids will be like as they grow up. We've all heard them, right? Firstborns tend to be more responsible. Middle children are the rebels. And the last born is usually the most free-spirited and confident. It's always interesting to see how people fit into the birth order stereotypes; obviously, it's not an exact science, and kids grow up to be who they're going to be, regardless of birth order. But as it turns out, there is some science behind it. Recently resurfaced research suggests that firstborns are indeed overachievers, and may actually be more intelligent than their siblings. Just don't tell your oldest brother or sister about this, you'll never hear the end of it.
The study, published in The Journal of Human Resources in 2016, suggests that firstborn kids may actually be more intelligent than their siblings. It doesn't have anything to do with genetics, though. It can be explained by parenting behaviors, and how firstborn and subsequent children are parented.
According to researchers Jee-Yeon K. Lehmann, Ana Nuevo-Chiquero and Marian Vidal-Fernandez, latter-born children tend to score lower on cognitive assessments at ages as young as 1 year old. Furthermore, that gap in cognitive assessment gets bigger until kids enter school, and actually remains significant in later years.
But again, there doesn't seem to be a genetic component. Instead, according to the study, it appears as though parental behaviors contribute to the gap, and it can start in pregnancy. First-time mothers tend to be more cautious, and first-time parents of one child tend to have more time to spend to provide crucial cognitive development stimulation. In subsequent pregnancies, mothers tend to take more risks, are less likely to breastfeed, and less likely to provide the same attention and stimulation.
Of course, we all know that older siblings can also be crucial for child development. But the variations in parent behaviors can have an impact on development in firstborns and latter-born children.