By Stacey Carter

Forget your Big Three—the newest compatibility factor? Birth Order Theory. From the oldest daughter’s eternal martyrdom to love languages tailored to your sibling type, the idea that your family dynamics shape who you’re attracted to is doing the rounds on social media. 

Just like your star sign supposedly influences who you get along with, your place in the family is being treated as a blueprint for your emotional quirks—and as a way to navigate dating. 

Some argue that birth order theory is another cosmic explanation for why we vibe (or don’t vibe) with certain people. But unlike astrology, it’s rooted in psychology. In fact, experts agree that your family position does influence your personality traits. But by how much? Well, that part is still up for debate.

How birth order theory came to be 

Birth order theory hasn’t materialized out of nowhere. The reality is that researchers have been looking into its influence on our personality traits for decades. And there are even studies that suggest there’s a link between birth order and specific personality traits. 

A 2007 study published in the Journal of Research in Personality found that eldest children score higher in traits like conscientiousness, leadership, and assertiveness because they often take on more responsibility at a younger age, which helps develop these traits early on. When we look at other siblings through this lens, it becomes clear that personality traits are often formed via our family dynamics. Think about it: if you’re a middle child, you’re probably used to balancing out different sibling personalities, so you’re likely more adaptable, diplomatic, and skilled at negotiation. And if you’re the youngest? You’re probably treated with a bit more leniency and attention, which means you’ve likely mastered the art of knowing how to get what you want when you want it.

However, the link between birth order and romantic compatibility isn’t exactly clear-cut. Some studies suggest birth order might have only a small impact on personality, while other factors, like family environment and parenting style, could have a much bigger influence. So, hold off adding “Eldest Sibling Seeking Eldest Sibling” to your profile—for now, anyway.

Should you let birth order theory influence who you date?

But what do relationship experts have to say about all this? Chantelle Otten, Bumble’s resident Sexologist, explains, “Birth order theory illuminates our understanding of how our position in the familial constellation can leave imprints on our relationship habits.” Essentially, it suggests that whether you’re the eldest, middle, youngest, or an only child, your role in the family can shape how you approach love, communication, and conflict in romantic relationships.

But here’s the catch: Experts like Otten are quick to emphasize that birth order shouldn’t be seen as a hard-and-fast rule for dating. Recent studies back this up. A 2020 article in Science Direct noted that while birth order could influence personality traits, it doesn’t necessarily dictate who you’ll be compatible with romantically. Basically, why you like who you like is far too nuanced to be determined by who got the last slice of pizza growing up.

“Your birth order may predispose, but it does not predetermine,” Otten adds. “You hold the power to navigate, negotiate, and nurture your dating life in your own unique way.”

While experts believe that birth order might have a slight influence on personality traits, most agree it’s not as significant as other environmental and genetic factors. 

What does our love for birth order theory say about us? 

Perhaps the real question here is: what does our obsession with astrology and birth order theory say about us? Well, it likely points to our craving for structure and certainty in a world that feels chaotic. 

Research suggests that, during uncertain times, we seek frameworks that simplify the complexities of human behavior. The reality is that personality systems provide a comforting sense of order and that people often turn to such theories when faced with ambiguity. In other words, life is messy, relationships are hard, and birth order theory offers a tidy little framework to make sense of it all. 

While the theory makes for an interesting conversation starter, it’s not the key to understanding compatibility. Sure, it sheds light on family dynamics—and offers some insight into why eldest daughters find people who actually make plans, rather than just talking about them, practically irresistible. But if compatibility were that simple, we’d all be discussing it from the get-go. The truth is that it’s not your birth order that matters when you’re dating—it’s finding someone who loves you for you.