As an activist against email spam, 50-year-old Montrealer Neil Schwartzman had seen his fair share of unsolicited emails. But he received one email this May that stuck out.

"I think you're my brother," a stranger wrote. And sure enough, that email was true.

Schwartzman was given up for adoption when he was 10 days old and never knew who his mother was, despite attempts to find her.

Thanks to a website that matches people's DNA, Schwartzman learned he had an older sister, 53-year-old California resident Jolie Pearl, formally of Montreal.

Schwartzman joined the website 23andMe.com three years ago. The site takes a DNA sample and compares it to other members.

Despite there only being about 100,000 users registered on the website around the globe, one of them was his long-long sister, who joined the site this May.

"I did this because I'm adopted and really didn't have a medical history," he told CTV News Channel Friday. "I was looking for my mother, there are no records, mine was a private adoption, and all of a sudden I get this email saying, ‘I think I may be your sister.'"

Pearl was on the website, not looking for any long-lost siblings, but because she had an interest in genealogy.

"I did it because I was interested in researching family history, I had no idea that I had a brother," she said from CTV Montreal's studio, alongside her brother.

The pair exchanged emails and then, using an advanced genome comparison, the website was able to confirm that they were siblings.

"It was amazing, I never thought there was other people out there related to me, it was a stunning, wonderful moment," said Schwartzman, the executive director for the Coalition Against Unsolicited Commercial Email.

Adds Pearl: "I was very, very surprised, but it also meant I had to examine my life in Montreal before we moved to California, it raised many questions."

Pearl confronted her mother, who admitted that she gave up a baby boy for adoption in 1960 to another couple, and kept it a secret.

The newly-found siblings continued to talk after the discovery. The pair soon met, along with their mother, in California where Schwartzman had a previously-scheduled conference.

"We went out to dinner . . . I was late and the first thing he said to me was ‘Oh, you are small, just like me," Pearl recalled. "I guess that's a family characteristic.

"We went to dinner and we talked for five hours straight."

The siblings say they almost immediately had a "deep, nuanced" relationship and stumbled on some interesting connections.

Relatives say they have similar hand gestures when talking, and oddly, both have taken the same career paths, as they are union activists.

The website 23andMe.com was co-founded by Anne Wojcicki, who is married to Google co-founder Sergey Brin. Google has invested in the company.