One possibility, proposed by the psychologist Robert Zajonc, is that older siblings consolidate and organize their knowledge in their natural roles as tutors to junior. These lessons, in short, benefit the teacher more than the student.
Another potential explanation concerns how siblings find a niche in the family. Some studies find that both the older and younger siblings tend to describe the firstborn as more disciplined, responsible, high-achieving. Studies suggest — and parents know from experience — that to distinguish themselves, younger siblings often develop other skills, like social charm, a good curveball, mastery of the electric bass, acting skills.
....Firstborns have won more Nobel Prizes in science than younger siblings, but often by advancing current understanding, rather than overturning it.
All good stuff. But this has been irking me and bugging my brain lately. And it's not because I'm a 3rd child and feeling defensive about my own traits - because I freely acknowledge I am not the sharpest crayon in my family, and the data makes a lot of good points.
I'm irked as a mother... like, if my other children are going to have lower IQs, why try? I'm destined to fail? It doesn't help that my eldest is far smarter than I am. They put her a grade ahead, and I have always been trailing the pack. But what gets me is this:
The Dude had a speech delay, and has proven to be an incredibly unique human from the get-go. When we were finding out all the things that made him tick through therapy and prayer*, I was told by more than one friend (read:non-professional) source that he wasn't talking as young as WonderGirl had because I'd simply spent more time and energy with her. And that hurt - it still hurts, and is just untrue. WG is brilliant, but because of who she is, not anything I did. I spent the majority of the first 2 years of her life sobbing on the couch while she watched hours of PBS kids. A few times sobbing on the kitchen floor. You get the point. The fact she is as bright as she is is a miracle of biology, not environment.
So she's a freakin' genius, but I really hate it when people assume it's because she was given more than her siblings. I was doing some looking back on things, and found the Dude was reading a year before she was, and even sooner on the violin and piano. And you guys, he is a really, really good little pianist. It's freaking me out a little bit. The truth is, the Dude simply got a better mother early on the WG did. And I watch Thing 3 watching the Dude's piano and violin lessons with this laser beam of attention. He's a Suzuki sibling dream!
Not that this was much of a rant, but /rant.
* by the way, the Dude has caught up verbally. And WON'T. STOP.