Jessica Wynn

I mean, do they ever try to copy the way you do things, like a little left-handed mimic phase or anything?

Right.

Yeah, they probably don't have that concept yet because it is just a natural dominant thing we do.

And it would be a significant challenge to, as an adult, try and use a less dominant hand because handedness is decided long before anyone picks up an instrument.

And studies show that in the womb, fetuses start showing little quirks like a head-turning bias, meaning some turn to the right more often, which means they get more sensory feedback from that side.

That feedback reinforces right-hand use later on, and vice versa, left-turners end up left-handed.

Yeah, because there's balancing involved.

Yeah.

Yeah, not interested.

Yeah, that's hilarious.

But another strong indicator is a fetus's preference for sucking its left or right thumb, like I said.

So the preference is maintained throughout pregnancy, but handedness is thought to be decided before our thumbs even develop.

It's using the ultrasound studies.

Researchers can observe a fetus's earliest arm movements as early as 10 weeks to determine a preference.

So a fetus will often make faster, more precise movements with its dominant arm.

And by 18 weeks, the hand's structure is developed and one side will reach toward their face, mouth, and eyes more.

Cool.

Yeah.

I mean, it's still kind of a chicken and egg problem, though, because we don't know if the fetus is positioned that way because it's predisposed to be left handed or does the position create preference.

Pink, blue, or southpaw.