Lucy Greenwell

Maybe she's better off not knowing.

But while she's thinking about it, Laura gets a message, out of the blue.

It's from someone we're calling Sam.

He says he's just come across Laura's post, the one Laura had written on that family reunion site nearly 10 years earlier in 2010, asking if anyone remembered a nanny who had found a baby in the 1980s.

Laura had included the nanny's unusual surname.

And it was when Sam googled himself, hey, we've all done it, that a link to the post popped up.

It popped up because they share a surname.

And they share a surname because the nanny is Sam's sister.

And he says something incredible.

He says he's always suspected that his sister didn't just find the baby.

All along, he's had a hunch that it was her baby.

After talking to Sam, Jess's sister Laura goes into overdrive.

Standing in her kitchen, she spits into a tiny plastic pot, twists the lid tight, drops it into an envelope.

At the end of her lane, she posts it.

She tells me she was excited to find out where her DNA was from.

Will she find something surprising, like Laura, who discovered that she was half American?

She's not thinking about those.

Because if you've abandoned a baby and then kept quiet about it for decades, you're hardly going to go and share your DNA with a commercial database, right?

It's 35 years since Jess was discovered on that verge, but it's at this moment, Jess's saliva sealed in that plastic vial, that something unstoppable begins.

Six weeks go by, an email arrives.