There were whispers.

The four-time Olympian and 7-time medalist in cross-country skiing, including three gold medals, Eero Mantyranta of Lankojarvi, Finland was a legend in his country and his sport. But he could not outrace the rumors of blood doping when he competed.

As a child, everyone in Lankojarvi skated and skied, but Mantyranta excelled, winning his first cross-country ski race at the age of 7, and then dominating all takers into his early teens. Eventually he was able to find employment as a border patrol guard, who got around his territory on skis. As a twenty-year old, he made the Olympic squad that traveled to Squaw Valley, California for the 1960 Winter Games, snagging a gold medal in the 4x10km cross-country ski event.

Four years later at Innsbruck, Austria, Mantyranta was one of the Games’ stars, taking two more golds in the 15 and 30-km races, as well as a silver medal in the 4x10km relay. And in his third Olympics, Mantyranta tool home a silver and two bronze medals.

All that success only encouraged the rumors. After all, it was known since he was a teenager that Mantyranta had “high hemoglobin and far more than the usual amount of red blood cells,” according to David Epstein, author of the fascinating book, The Sports Gene: Inside the Science of Extraordinary Athletic Performance. “Normally, those are signs that an endurance athlete is blood doping, often with a synthetic version of the hormone erythropoietin, or EPO. EPO signals the body to produce red blood cells, so injecting it spurs an athlete’s own body to bolster its blood supply.”

But also according to Epstein, the rumors were untrue.

First there were indications that other members of the Mantyranta family also rested for high levels of hemoglobin, but because there were little ill effects from higher-than-average hemoglobin levels, doctors were never concerned. But this coincidence made hematologists from Finland wonder. After putting the Finnish Olympian through additional blood testing, it was learned that in fact Eero Mantyranta had very low levels of EPO, and that when most people stopped producing hemoglobin based on what the body considered enough, Mantyranta’s body was genetically designed to continuouisly pump out hemoglobin.

And more hemoglobin meant not only very ruddy cheeks. It also meant high levels of oxygen circulated inside Mantyranta, a significant advantage that allowed him to ski faster and longer than almost every other cross-country skier. Most certainly, Mantyranta’s singular drive to train and increase his performance as a cross-country competitor was essential to his Olympic success. But most certainly, so was this genetic advantage.

Here’s how Epstein remembered Mantyranta in this obituary, when the great cross country skier passed away in 2013.

Being born with talent is one thing; alchemizing it into Olympic gold entirely another. And though I drew attention to Eero’s startling biology, that’s worth remembering as well. I’ll remember Eero the way he was when I met him. A jovial and remarkable-looking man, with dark, slicked-back hair and prominent cheekbones that seemed to pull at the corners of his mouth, giving him a slightly inquisitive look. There was a thickness about him, a barrel chest and bulbous nose. I remember when he shook my hand, I felt as if he could’ve crushed my fingers, and I noticed that his middle finger was bent at a right angle from the top joint. He spent the brief period of Arctic winter sunlight that day working in his reindeer yard. I thought he must have been the strongest seventy-three year old I had ever met. That’s how I’ll remember him.