As It Happens

Don't mind the smell of fish? It could be in your genes

If you ask most people if something smells fishy, they’ll be able to give you a straight answer. But those with a certain genetic mutation might not know what the heck you’re talking about. 

Icelandic researchers say some people have a genetic variant that makes the most pungent fish smell pleasant 

Dozens of varieties of fresh fish sit in open market-style aisles at Seafood City in Calgary. (Dan McGarvey/CBC)

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Kári Stefánsson sometimes wishes he had the genetic mutation that allows some of his fellow Icelanders to enjoy the smell of pungent or rotten fish.

He and his colleagues recently discovered that a small percentage of people born with a specific incapacitated gene either don't recognize the smell of stinky fish, or find it to be pleasant. 

This would have come in handy when he was a kid at Christmas and his parents prepared the traditional Icelandic holiday meal of skata, or fermented stingray.

"The smell of it, I'm sure that it violates the international record on chemical warfare," the neurologist told As It Happens host Carol Off.

"Mutations are in your genome from your birth, and then you die. You cannot just switch them in and out around Christmas, unfortunately."

The genetic study of 11,000 people was published Thursday in the journal Current Biology. 

Like caramel or roses 

Stefánsson, founder and chief executive of the biopharmaceutical company deCODE genetics, has long been studying the human genome. 

In this latest research, scientists asked participants to take whiffs of Sniffin' Sticks — pens imbued with synthetic odours mimicking cinnamon, banana, peppermint, lemon, licorice, and fish. They were asked to identify the scents, then rate them on their intensity and pleasantness.

The fish smell was the most widely identifiable, and consistently rated the least pleasant — except among a small group of people who were born with a genetic mutation that incapacitated their TAAR5 gene.

Workers at an Icelandic fish factory clean cod in Grindavik. (Olivier Morin/AFP/Getty Images)

Not only were carriers of the broken gene less likely to identify the smell of stinky fish, some of them said it smelled like potatoes, ketchup, caramel or even roses. 

"They would report it as being relatively pleasant, however unpleasant it may smell to me and you," Stefánsson said.

A genetic advantage, depending were you live

The mutation was found in 2.2 per cent of Icelanders, 1.7 per cent of Swedes, 0.8 per cent of Southern Europeans and 0.2 per cent of Africans.

That North-South discrepancy makes sense from an evolutionary standpoint, says Stefánsson.

"We have lived in Iceland for 1,100 years and we have lived mostly on fish for this very long time," he said. "So if you were born with this mutation, you have a certain advantage, in which it was probably not quite as intolerable to have nothing else to eat but fish."

The ability to detect stinky fish is probably an evolutionary gift for most people. It's the body's way of protecting us from eating something rotten and potentially dangerous.

But in Iceland, where preserved fish is a dietary staple, a functioning TAAR5 might actually be a hindrance. 

"It may come to you as a surprise, but 1,100 years ago, we did not have refrigerators. So we had to serve the fish by using all kinds of strange methods that included letting the fish rot a little bit,"  Stefánsson said. 

Those traditions have carried into modern cuisine, much to Stefánsson's chagrin. 

"I have no useful mutation, unfortunately."

Written by Sheena Goodyear. Interview produced by Chris Harbord. 

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