Up until recently, there was no concrete evidence that one’s birth order has any bearing on their personality or intelligence.

But that didn’t make sense. I mean, we all know – many of us through firsthand experience – that family positioning has a massive impact on one’s life.

Joshua Hartshorne, psychology professor at Boston College, wasn’t satisfied with the lack of evidence either. And so, along with a few colleagues, he set out to find a definitive link.

In 2009, Hartshorne’s team shared that definitive link in a study. It’s a pretty complex link based on several factors, one of which is a child’s need to diversify their interests based on a family’s limited resources.

This validates prior speculation from a number of psychology and sociology experts.

What Does This Mean For You?

Of course, it all depends on your birth order! Let’s dive right into it.



According to Dr. Frank J. Sulloway, firstborns are often ambitious, responsible natural leaders. This is because firstborn children tend to become ‘surrogate parents’ when their siblings arrive. They’re no longer the baby of the family but are instead expected to help out with chores and caring for the new baby.

Firstborns also tend to be more intelligent than their siblings; according to a 2007 Norway study. They typically have two or three more IQ points than the next child.

Middle Children


According to Dr. Catherine Salmon, middle children tend to be masters at compromise and negotiation. This is because they have neither the rights of the oldest child or the privilege of the youngest.

Middle children also tend to be social butterflies. Because their parents are more likely to be concerned with the oldest or youngest child, they’re often forced to rely on friends for support.

Babies In The Family


Dr. Catherine Salmon also weighs in on how being the baby of the family impacts personality. According to her, the youngest child tends to be the free-spirited risk-taker in the family. They’re also often very charming.

“Parents are more lenient, so youngest kids tend to be less rule-oriented, and yet they still get lots of attention,” Salmon says.

Only Children


Only children tend to possess characteristics similar to that of firstborns. They’re ambitious and responsible due to the greater pressure that falls on their shoulders; there’s no one else to make the family proud or get chores done.

They’re not entirely the same as firstborns, though; only children tend to be more motivated and successful than kids with siblings.

So, do you agree with these findings? Do they accurately describe you based on your birth order? Let us know in the comments and be sure to pass this post along to your friends – and your siblings!

Joshua Hartshorne
Born To Rebel by Frank J. Sulloway
The Secret Power of Middle Children by Catherine Salmon and Katrin Schumann