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The Jordan Harbinger Show

1272: Left-Handedness | Skeptical Sunday

The Jordan Harbinger Show

Jordan Harbinger

Education, Science, Business

4.8 • 12.3K Ratings

🗓️ 18 January 2026

⏱️ 52 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

Scissors, spiral notebooks, cultural taboos — lefties have it rough. Jessica Wynn explores why 10% of us are southpaws here on Skeptical Sunday.

Welcome to Skeptical Sunday, a special edition of The Jordan Harbinger Show where Jordan and a guest break down a topic that you may have never thought about, open things up, and debunk common misconceptions. This time around, we’re joined by writer and researcher Jessica Wynn!

Full show notes and resources can be found here: jordanharbinger.com/1272

On This Week's Skeptical Sunday:

  • Left-handedness isn't controlled by a single gene — it's a cocktail of genetics, prenatal environment, and random brain development. The rare gene variant TUBB4B shows up three times more often in lefties, but even identical twins sharing 100% of their DNA can have different dominant hands.
  • Your handedness was essentially decided before you were born. Ultrasound studies reveal fetuses showing consistent hand preferences by 18 weeks — those who suck their left thumb in the womb typically become left-handed. Your fetal position and which direction you turned your head may have sealed your southpaw fate.
  • Left-handers possess a larger corpus callosum — the neural bridge connecting both brain hemispheres — enabling faster communication between the two sides. This biological quirk gives lefties advantages in multitasking, creative problem-solving, and activities requiring rapid information processing like video game
  • Cultural conditioning has historically punished left-handedness, associating it with everything from uncleanliness to witchcraft. Schools once forced children to switch hands, and in some cultures today, using your left hand for eating remains taboo — a lingering echo of pre-toilet paper hygiene practices.
  • Celebrate your brain's beautiful asymmetry — whether you're a lefty or righty. Try using your non-dominant hand for everyday tasks on August 13th (International Left-Handers Day) to appreciate how deeply ingrained handedness really is. It's a humbling reminder of how wonderfully weird human development can be.
  • Connect with Jordan on Twitter, Instagram, and YouTube. If you have something you'd like us to tackle here on Skeptical Sunday, drop Jordan a line at jordan@jordanharbinger.com and let him know!
  • Connect with Jessica Wynn at Instagram and Threads, and subscribe to her newsletters: Between the Lines and Where the Shadows Linger!

And if you're still game to support us, please leave a review here — even one sentence helps!

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Transcript

Click on a timestamp to play from that location

0:00.0

Welcome to Skeptical Sunday. I'm your host, Jordan Harbinger. Today I'm here with Skeptical Sunday

0:07.9

co-host writer and researcher Jessica Wynn. On the Jordan Harbinger show, we decode the stories,

0:12.5

secrets and skills of the world's most fascinating people and turn their wisdom into practical

0:16.5

advice that you can use to impact your own life and those around you. Our mission is to help you become a better informed, more critical thinker. And during the week, we have long-forms

0:24.7

conversations with a variety of amazing folks, from spies to CEOs, athletes, authors, thinkers,

0:29.6

performers. On Sundays, though, it's skeptical Sunday. A rotating guest co-host and I will break

0:34.3

down a topic you may have never thought about and debunk common misconceptions about that topic. Topics like astrology, recycling, chem trails, GMOs,

0:42.6

toothpaste, crystal healing, and more. And if you're new to the show or you want to

0:45.8

tell your friends about the show, I suggest our episode starter packs. These are collections

0:49.8

of our favorite episodes on persuasion, negotiation, psychology, disinformation, junk science, crime

0:55.0

and cults, and more. That'll help new listeners get a taste of everything we do here on the show.

0:59.2

Just visit jordanharbinger.com slash start or search for us in your Spotify app to get started.

1:04.8

Today on the show, it's possible you know someone who's left-handed, or maybe you're one of those

1:09.4

people who insists on announcing it every time you pick up a pen. Aside from the fact that lefties use's left-handed, or maybe you're one of those people who insists on announcing

1:10.9

it every time you pick up a pen. Aside from the fact that lefties use their left-hand

1:14.9

to write, play sports, do everyday tasks, you probably don't know much else about left-handed

1:19.8

folks. As a lefty myself, I'm also curious what makes me a lefty in the first place. What

1:24.8

gives us our handedness? To get to the right or left side of things

1:29.3

is writer and researcher Jessica Wynn. So, Jess, I'm left-handed. I'm just going to cut to the

1:33.7

chase and assume that makes me superior to most other people, correct? I think so, but you are in

1:39.0

good company. Okay. Lady Gaga, Obama, Jimmy Hendricks, me. So you're on the left side of things. Nice, but honestly,

1:47.3

it can be kind of a drag, scissors, they don't work, they don't fit. Spiral notebooks are some

...

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