Search icon A magnifying glass. It indicates, "Click to perform a search".
Business Insider logo
Newsletters
World globe An icon of the world globe, indicating different international options."
US Edition
Loading...

A top psychologist explains how birth order may affect your success

Actor-brothers Liam Hemsworth, Chris Hemsworth, and Luke Hemsworth.
Kevork Djansezian / Reuters

There's got to be something about birth order and success — why else would it be a staple of conversation on first dates and in networking events? — but science hasn't quite figured out what. 

It's a "widely controversial" field, explains University of Pennsylvania psychologist Adam Grant, but a worthwhile one for evaluating. 

In "Originals: How Non-Conformists Move the World," Grant takes a dive into birth order research. He unearths two surprising findings: many of the top base stealers in Major League Baseball history were younger siblings. The same holds true with top comedians. 

At the same time, studies indicate that first-born kids are more ambitious when it comes to advancing their education, score higher on IQ tests, and go further in business than their siblings. 

Older (and only) siblings tend to be more conventionally successful, Grant says. 

"They grow up in a world of adults who are generally smarter than children, and they want to please adults," he says. "And the way to do that is you succeed in conventional ways." 

But a lot of these birth order discussions are speculative. 

"It's really hard to test a lot of these mechanisms and the kind of careful research that needs to be done hasn't been done yet to really explain why," he says, "but I think there are a couple things that are likely to be going on."

That said, there are some compelling explanations for how birth order affects adulthood.

Evolutionary psychology (itself a controversial field) suggests the grown-up self results from the niche you pick. According to the theory, each kid is vying for attention of the parents, but they do so in different ways — carving out niches like Darwin's finches. One kid's an actor, another a star student, another an athlete; call it "Royal Tenenbaums" syndrome. The privilege of the first kid, then, is that she gets to stake out her niche before any competitors emerge. 

Similarly, older siblings have a big developmental advantage over the younger. It's hard to be stronger or smarter than your older sibling, but it's not that hard to be funnier. Thus all the younger-sibling comedians.

"You can be a baby and make your siblings laugh without even meaning to," he says. "The more you notice that people pay attention to me when I laugh as a toddler or make jokes as a toddler or do a silly thing, the more that gets reinforced."

At the same time, if you have a sibling that's a little bit better than you at a sport, that can be motivating: you'll be exposed to sports earlier, and constantly striving to meet a standard that's higher than what you would've had as the first born. (See Michael Jordan's older-by-eleven-months brother Larry. Their dad thought Larry was the son with the real talent for basketball). 

And when you're younger (especially when you're the third or fourth one born), you don't grow up in a world of adults; you grow up in a world of kids. So you're more likely to try and impress them.