With the gas fireplace humming in the background, all four members of the Tiessen household chat in the living room of their red-brick bungalow in Stoney Creek, Ont. The family photos on the mantle, along with the way in which they talk over each other without descending into argument, suggest they're tightknit. It's a comforting scene, but nothing about it screams "exceptional."

Yet the Tiessen's are exceptional — perhaps even unique — for reasons they are just beginning to uncover with the help of an American researcher.

Former professors Doug and Julie, who claim not to be artistic, have two art prodigies for sons. And it may be due in part to a lucky accident.

Josh, 17, paints rustic, detailed landscapes replete with soaring birds and brooding mammals, his work reminiscent of Toronto-born painter Robert Bateman (who has given him some tutoring).

Zac, 16, is a guitarist and composer who creates highly complex, but melodic heavy metal numbers on his laptop computer and already takes advanced theory courses through Boston's prestigious Berklee College of Music.

What is a prodigy?

According to Joanne Ruthsatz, an associate professor of psychology at Ohio State University, a prodigy is someone who achieves "advanced professional status" in a particular field before reaching adulthood.

One person in 5 million is a prodigy, she estimates. 

Though it's obvious the teens have talent in spades, it didn't dawn on Julie and Doug might have two bona fide prodigies living under their roof until they started corresponding with Joanne Ruthsatz, a psychologist who studies exceptional giftedness. The researcher from Ohio State University sent Julie an email in January after discovering articles about Josh's art on the internet.

They arranged for Ruthsatz to drive up to Stoney Creek for the Feb. 8 weekend, which ended up bringing record-breaking snowfall to much of southern Ontario.

Despite weather, the university professor made it. During her stay, she interviewed the Tiessens for hours about their personal histories and subjected Josh and Zac to several tests.

As it happened, the purpose of Ruthsatz's visit was not to determine whether Josh and Zac qualified as prodigies. She had already made up her mind on that matter, something that caught the brothers off-guard. 

"We were skeptical and both asking questions like, "do you know they're prodigies when you visit?" Josh recalled.

"The first thing she said…" he started saying, before his brother jumped in.   

"…was 'I wouldn't be coming if you weren't,'" Zac blurted, finishing Josh's sentence.

Ruthsatz's revelation came as a surprise for Josh, even though friends and reporters have gushed about his abilities for years.

Born in Russia, where his parents taught until the early 2000s, Josh started drawing as a toddler. His interest in art continued to accelerate when the family returned to Canada, when he was six.

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Josh Tiessen works on a charcoal sketching in his paint studio. He donates some of the proceeds from the sale of his art to research into Lyme disease, which afflicts both of his parents. (Cory Ruf/CBC)

"I started getting press when I was 10 or 11," said the elder Tiessen brother. "They started calling me a prodigy. I took it pretty lightly, though. I didn't know for sure or not if was one."

Related: Stoney Creek teen's art hangs with Van Gogh at National Gallery

Ruthsatz's assessment was ever more shocking for Zac, whose musical prowess precipitated later on and thus, wasn't as well known.

"I think everyone's seen that I've been living my brother's shadow for a couple of years now, just because he's gotten so much press attention," he said.

"I think with me starting later, I never expected myself to be viewed on the same level."

Creating art, advancing science

By participating in Ruthsatz's study, the Tiessens are helping to develop a clearer picture of how "prodigiousness" is created. The psychologist visits child prodigies, as well as adults who were prodigies as children, across North American.

She measures their IQs, visual-spatial skills and other indicators to establish a profile of children who are exceptionally gifted in the fields of art, music and mathematics.

Though there are differences between, for example, youngsters who excel in music and those who are elite sculptors, Ruthsatz's research suggests that most child prodigies have a few key common denominators. 

In a paper published last year in the academic journal Intelligence, she and co-author Jourdan B. Urbach wrote that prodigies shared three major characteristics in terms of how they think.

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Joanne Ruthsatz is an assistant professor of psychology at Ohio State University. (Handout)

First, the prodigies they studied all possessed "elevated" — though not necessarily extraordinary — intelligence as a baseline.

But what made the wunderkinds stand out was their working memory. It's a term that refers to a person's ability to manage tackle multiple cognitive processes at the same time. Perhaps a good comparison is the random-access memory (RAM) in a computer, which allows the machine to juggle multiple applications in short order or at the same time.

Each prodigy, the scholars wrote, ranked in the 99th percentile in terms of their working memory. 

In addition, on average, the gifted participants scored markedly higher than the control group on tests that measure for autism. However, according to Ruthsatz and Jourdan, the "prodigies displayed only a very minimal level of the deficits commonly associated with autism," including barriers to social interaction, while strongly exhibiting some of the more valued traits — namely, the capacity for extreme attention to detail.

These results — along with the finding that half of the participants had autism in their families — lend credence to theory that there is some sort of genetic link between the disorder and prodigiousness. By observing cases like the Tiessens', Ruthsatz is exploring the connection further, with the aim of unlocking the mysteries surrounding both conditions.

Don't get the impression, though, that Ruthsatz and her colleagues in the scientific community are the only direct beneficiaries of the fact-finding process. Instead, in much the same way that the Tiessens are helping to improve scientists' understanding of the human brain, Ruthsatz has, perhaps unwittingly, helped the Canadian clan arrive at profound discoveries about their own (rather improbable) past.

'Something switched in my brain'

Up until recently, a big mystery for the Tiessens was the question of why Josh took to art, as Julie put it, as soon as he could hold a "fat crayon," while Zac's focus and drive came much later, when he was in his early teens.

"He was a bit A.D.D.," Julie said, recalling her youngest son's childhood behaviour. "We never had him tested [for attention deficit disorder], but he was all over the place."

Moreover, despite a baseline aptitude for music, younger Zac showed little interest in the pursuit.

"In my elementary years, when my mom was homeschooling us, she would do music with my brother and I," he said. "However, I hated it for some reason. It was my most hated subject. I was just totally … I just couldn't stand it."

Then, at age 13, he said, "Something switched in my brain, to like a polar opposite."

Zac began taking out books on music theory and spent hours a day plucking out melodies on a starter acoustic guitar he'd been given. For years since, the family has treated Zac's sudden interest in music as an organic stage in his development, never singling out a catalytic event that might have caused things to change. 

Until Ruthsatz came calling.

While sharing their story with their American guest, the Tiessens came to a stunning realization: Zac's transformation roughly coincided with an injury he suffered at age 13. Still in his rambunctious phase, Zac had attempted to leap over a box during a youth group session at his church, landing headfirst on the hard floor. He suffered a concussion, his seventh and one of his worst.

"Joanne is still researching this, but my concussions, we believe they made me almost switch from being sort of musical but not really wanting to do it, to very focused," Zac said.

Putting the pieces together

Ruthsatz hypothesizes the youngest Tiessen may have experienced an offshoot of a condition called acquired savant syndrome, which occurs when a person who suffers a major brain injury develops some sort of special ability or talent. Savants who thrive in the areas of art in music, she said, have often sustained trauma to the left sides of their brains, rendering the right hemisphere, which is associated with artistic creativity, dominant.

'They have one of the most interesting stories I've ever heard.' —Joanne Ruthsatz, Ohio State University

During his stunt in the church basement, Zac did hit his head on the left side. Unlike acquired savants, however, he doesn't show signs of cognitive impairment.

"I'd call him an acquired prodigy, not acquired savant," Ruthsatz quipped, adding the brothers may have code in their DNA that protected Zac from greater harm.

"What I think is there's some sort of genetic modifier that in the event of left hemisphere damage that causes the right hemisphere to compensate without disabling him."

In their weekend together, Ruthsatz and Tiessen arrived at another startling theory: Josh's prodigiousness, though apparent virtually from birth, might have stemmed from trauma as well.

Julie said her pregnancy with her eldest son was a difficult one — she suffered preterm labour and had to make several trips to the hospital in the months before Josh was born. More frighteningly, though, Julie fell onto her pregnant belly while she, Doug and her mother-in-law struggled to fend off a masked intruder who had tried unsuccessfully to break into their home.

"They have one of the most interesting stories I've ever heard," Ruthsatz said. "It should be a book. It should be made into a movie."

Whether or not their story is fit for the silver screen, the Tiessens are grateful for Ruthsatz's help in making sense of it. 

"She helped us put the pieces together," said Doug, a hint of incredulity in his voice.

"We sat in here in the morning piecing all of this together and we were like, 'Whoa,' " Julie chimed in. 

"We didn't know all of these stories in our lives would have such an impact."

Josh Tiessen's art will be on display at Hamilton's Green Smoothie Bar (236 James St. North) during the James Street North Art Crawl on Friday. Zac Tiessen will be performing his music there, too. Doors at 7 p.m.