What Being a Younger Sibling Says About You, According To Science

From the Solanges to the Liam Hemsworths, younger siblings can often struggle to nab the limelight from their older counterparts. Yet old wives' tales say that the babies of the family are more attention-seeking, rebellious, and spoiled. But does science actually back any of these assumptions about younger siblings up?

Older siblings seem to get the best deal out of families: multiple studies seem to demonstrate that the older kids in a family have higher IQs, and are more likely to be professionally successful, according to a study in 2014 — particularly if they're women. Yes, Hillary Clinton's presidential run may be, in some tiny way, due to the fact that she was a first-born. It's Beyonce syndrome, and it seems to leave younger siblings out in the cold. However, there are definitely advantages to being lower in the birth order — though they may appear in unexpected ways.

As the younger sibling of an older brother (with whom I fought continually), it's been an interesting and slightly bizarre journey leafing through studies showing me just how much he's affected my life. (Aside from accidentally chipping my front tooth once. Not forgiven, Sam.)

Siblings definitely affect our lives, but scientific results about just exactly how may surprise you. So here's what science says about the life of a younger sibling.

1. We Might Be More Likely To Commit Suicide

Let's start out with a cheery one, shall we? A Swedish study from May 2014 has posited that younger siblings are 18 percent more likely to commit suicide than older ones — and it doesn't seem to matter what you do in life or how successful you are. The scientists used the Swedish government's censuses on siblings born between 1932 and 1980, and looked at how their lives developed between 1981 and 2002.

Not only was suicidality more pronounced in younger siblings, it got worse the later in the century you were born. In 2009, another study of 2,500 children in psychiatric wards showed that middle children were the most suicidal as kids — but as you reach adulthood, it seems it's the younger ones that are most vulnerable.

So what's going on? The leader of the study, Mikael Rostila, blames lack of closeness to parents and bullying by older siblings. "Lower levels of attachment to parents because of restrictions in quality time could give rise to emotional and behavioral problems, separation stress and psychiatric disorders," he said, "thereby contributing to a higher suicide risk among later-born siblings."

2. We Grow More Slowly — Literally

I'm 5'10", but according to this study I could have been 6'0" if it hadn't been the curse of Fate to be born after an older brother. A study in the UK in 2007 looked at the comparative heights of siblings across thousands of families, and found something surprising: younger siblings were proportionally shorter than their elders. And it was particularly pronounced when the older siblings were boys.

The explanation seems to be about resources. Older siblings, it seems, take up both more attention and more food, and boys in particular are seen as more "demanding" to raise. Interestingly, older siblings got their growth stunted with the addition of a sibling a little bit too — but only before the age of 10, when they shot up to "normal" height. Darn them.

3. We Get Less Parental Attention

As the previous studies have shown, older siblings have a nasty habit of taking up all the space. The study that's now famous for revealing that first-borns really do get sh*t done (every man that walked on the moon was a first-born, as are Angela Merkel, Oprah Winfrey, Barack Obama, and Jane Goodall) also uncovered an interesting potential reason for why younger kids get left behind: parental investment.

The scientist in charge, Feifei Bu, studied 1,503 sibling groups and 3,532 individuals, and thinks that the disparity she discovered — firstborns are 16 percent more likely to go further with their education than their younger brothers or sisters — comes down to attention from parents.

"It could be that the parents simply devote more time and energy to them — it could be they are actually more intelligent," Bu said. "For me, I tend to lean towards the theory that parental investment is possibly at work here."

4. We Tend To Be Risk-Takers, Explorers, And More Creative

Frank Sulloway, an adjunct professor at UC Berkley, is one of the world's foremost authorities on birth order from a Darwinian perspective, and he's discovered some pretty interesting things about younger siblings' personality traits. According to his studies, consolidated in the classic Birth Order (1999), the younger sibling personality is adventurous, risk-taking, and full of exploratory zeal — and provocation.

Instead of the "responsibility" and parentally-approved excelling of the older sibling, Sulloway says, younger siblings try to find other ways to compete. “They are eking out alternative ways of deriving the maximum benefit out of the environment, and not directly competing for the same resources as the eldest," he says. Hence they tend to develop more "different" interests. (I'm a writer and my brother is a scientist, so this makes sense to me.)

He also, flatteringly, points out that while firstborns may get the Nobel Prize for science, they tend to do it with less imaginative thought and more improvement on what already exists — while the real leaps in innovation tends to come from younger siblings.

5. Our Older Siblings Really Mold Us In Creepy Ways

Our older siblings are massive influences on our young minds. Research has shown that we follow the sexual model laid out by our older brothers and sisters — if they keep their pants on, so do we — but their behavioral influence goes even further than that. They can shape us into geniuses or criminals, depending on which way they go themselves.

Smart older siblings have been shown consistently to motivate and improve the test results of younger siblings; a study from the University of Essex called it the "sibling spill-over effect," and noted that it's particularly strong in families living on fewer resources and closer to the poverty line. A high-achieving older brother or sister makes us push harder. But it can also go the other way: a 2014 study of the Swedish census showed that having an older sibling who'd committed a violent crime made it far more likely that you'd commit one too. We're impressionable types.

6. We Make Our Older Siblings More Expressive

Younger siblings have a positive effect on our elders too. Younger siblings tend to learn empathy from older siblings, according to a study from 1999, but we also teach each other through play. A study at the Center Of Research And Human Development in 2013 found that older and younger kids alternated between being "teachers" and "learners," and that younger siblings don't just sit passively and ask to be taught: we actively pursue our older siblings to explain stuff to us. So not only is sibling playtime helpful, it gives the eldest kids as much of a lesson as the young ones.

7. We Have Better Conceptual Knowledge

We also specialize in a different kind of knowledge: conceptual knowledge (what a circle is, or the difference between the days of the week), as opposed to procedural knowledge (how to do a certain process like tying your shoes). Maybe that's how Charles Darwin, the fifth youngest of six, got his start...

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Images: Beyonce/Instagram; Giphy