Heather Woock did an online DNA test. Then she discovered she had 62 half siblings.

One Christmas, Heather Woock’s husband gifted her an Ancestry.com DNA test.

She was interested in genealogy and her heritage results turned out exactly as she predicted: Scottish, English, Irish and Scandinavian.

And that was that, until Heather prepared for a holiday in August 2017.

What happens when you get the wrong sperm. Post continues after podcast. 

She received a bizarre message as she packed, from a stranger who claimed they were her half sibling. She asked her mum who said not to worry.

During her holiday, Heather received more messages from other supposed half siblings. It was… weird. But then her phone broke, and Heather spent the rest of her trip blissfully out of contact with the real world until she returned home to Indiana and replaced her phone. Then she found many more messages.

What the heck was going on?

As Heather – and tens of others – would learn was that this was no scam, or an unfortunate mistake, as she’d first assumed. They were all half siblings. They all shared the same father – a man named Dr Donald Cline.

Cline opened his infertility clinic in Indiana in 1979. He had told the women who came to him for help that he used the sperm of anonymous medical residents that resembled their husband, and in some cases they were actually told that they would get the husband’s sperm, Dr Jody Madeira of Indiana University told Mamamia‘s daily news podcast The Quicky.

But Cline also inseminated women with his own sperm. In total, Dr Madeira said Cline had fathered approximately 63 children.

"He has given a number of reasons," she explained. "The first is he essentially didn't want to let people down when they came to see him. If he couldn't obtain a donor, he hated to turn women away, he knew how much they wanted a child. That makes him seem like a doctor that was really motivated by the best interests of his patients.

"He's given some other answers. Apparently he used to do abortions in the 1970s and he's told people allegedly he wanted to atone for that behaviour. He has intimated most often that it was just a business decision, in the sense that he didn't want to turn women away because he didn't want to disappoint them."

In September 2016, Cline was charged with two counts of felony obstruction of justice. Ultimately, he was fined just $500 and given a year probation. He lost his medical licence, but he'd been retired since 2009.

Indiana's laws were not strong enough to charge Cline with any other crime, but Heather and another of Cline's children Matthew Smith have been working to pass legislation that would allow prosecutors to charge people for fertility fraud, the Indy Channel reported.

Dr Madeira believes that without the popularity of DNA tests like Ancestry.com and 23andMe, Dr Cline would never have been found out. He could've been discovered as a person's father with a paternity test, but anonymity laws would've kept his identity secret and one person's DNA would not have linked to their other half siblings.

The top three DNA test companies - Ancestry.com, 23andMe and Family Tree DNA - hold the DNA information of 20 million people.

And while most of those people would've come out with results they more or less expected, many are discovering they or their parents are not who they thought they were.

So while you may be pleasantly surprised to realise you're a tiny bit Portuguese or intrigued by your Jewish ancestry, it pays to be prepared for information that could be more life altering when taking such a test.

"Folks have to get used to the idea that there might be skeletons in the closet that they'll find," Dr Madeira said.

"It's odd for anybody in particular to expect this - when you do these tests often times you're just doing it for a lark or you're doing it to find out genetic ancestry information - but I think more and more these long-lost relatives or adoptions are coming out."

And that'd mean a very awkward phone call to mum.