Jessica Wynn

Previous studies have found several genes that seem to be tied to left-handedness.

A breakthrough study published in Nature Communications Journal looked at over 350,000 people.

38,000 of them were lefties and over 300,000 righties.

They found that this rare variant showed up about 30%.

three times more often in left-handers.

Right.

And at this point, it's correlation.

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.

Right.

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.