Jessica Wynn
👤 SpeakerAppearances Over Time
Podcast Appearances
It's not the cause.
In fact, identical twins who share all the same DNA can still have different dominant hands.
So twins are always particularly interesting case studies.
And about 20% of twins are left-handed, higher than in single births.
That's how we know the environment and random development patterns matter just as much.
Genes are only part of the story.
So research shows that left handedness comes down to tiny random differences in our position in the womb.
Yeah, that's how it is.
Even your position in the womb, so whether you were facing left or right, plays a role.
It's like prenatal feng shui.
Yeah, I mean, that's not far off.
Ultrasound studies show fetuses start using consistent hand movements around 18 weeks.
Those who suck their right thumb in the womb usually grow up right-handed.
Those who go for the left thumb, left-handed.
It sticks.
I didn't even realize fetuses suck their thumb in the womb.
Yeah, they do.
I know, they do.
Well, we just see it really early.