This is Hidden Brain, I'm Shankar Vidantam.

A couple of months ago, we asked you to share coincidences you've experienced.

Lots of you called in with amazing stories.

Nestled among them, were two stories that themselves formed a coincidence.

So I was a student at the University of Rhode Island, and we were in this writing class.

This is Amanda Birch.

She was talking to the teacher of her writing class,

and the teacher mentioned that she lived in a small town in Vermont.

The same small town it turned out, where Amanda's mother had grown up.

The teacher asked Amanda what her mother's maiden name was, and Amanda told her,

She just kind of drops her pen and she goes, you're not going to believe this,

but I live in the house where your mother grew up.

The other listener who called us was Sarah Toproth.

She called us on a scratchy phone line from Paris.

Sarah's an American, but it's been living in France for several years.

She was at a house party and someone there told her that there was another American in the room.

So she went over to say hello.

They started talking and...

So it turns out that this girl that I met at this house party in Paris grew up in the exact same house

in Pichipsey, New York as my father.

What are the odds?

We thought we might find out.

...