Known as Wall Street’s oldest stockbroker, Irving Kahn died earlier this year at the age of 109. He was born in 1905, made his first trade in 1929 before the Great Depression hit, and continued to work for years after celebrating his 100th birthday. Remarkably, Kahn and his three siblings all reached the centenarian mark (age 100 and up) while remaining relatively alert, active and healthy.

But as incredibly age-defying as they were, none of the Kahn siblings reached supercentenarian status — 110 years and older — in what appears to be a much harder feat for the human body to accomplish. While the Census Bureau reported about 50,000 centenarians living in the United States in 2010, there are only 50 to 80 supercentenarians in the entire world.

So what does it take to live to 110 years old and beyond? Is it a unique genetic profile, healthy habits, or simply luck of the draw?

The answer is far from simple, as aging researchers have discovered, and probably entail all of the above to some extent. But one thing can be agreed upon: supercentenarians aren’t your average human beings.

The vast majority of us have a set of genes that will allow us to reach a ripe old age somewhere in our late 80s and early 90s. Whether your death comes sooner or later than the next person is largely dictated by your lifestyle and environment, with harmful things like smoking and drinking essentially fighting against your genes to lower your lifespan. But on the other hand, adding more positive behaviors (e.g. exercise, diet, stress management) might tack on a few years — but it won’t make you a supercentenarian.

“Healthy living, diet, exercise — that sort of stuff will benefit you, and you might lead a life longer by maybe 5 years,” said geneticist Stuart Kim of the Stanford School of Medicine. “But to live 30 years longer, you probably need a different genetic background.”

Reports of the world’s longest living person, 122-year-old Jeanne Calment, all say she frequently enjoyed cigarettes and port wine. Helen Reicher, Irving Kahn’s older sister who died just shy of her 110th birthday, smoked daily for more than 80 years. As much as we’d like to think this gives us a free pass to indulge, stories like these just reinforce the theory that supercentenarians likely possess a special resilience to disease written in their genomes.

“To live to about the age of 90, 20-30 percent of that is going to be genetics, and 70-80 percent is going to be your health behaviors and your environment,” said Thomas Perls, Professor of Medicine and Geriatrics at Boston University. “If you want to live beyond 90, then I think there’s this growing genetic component that you don’t necessarily have a choice over.”

In a 2012 study published by the journal PLOS ONE, Perls and his colleagues looked for genetic signatures of exceptional longevity in the genomes of 801 centenarians. No single gene stood out, but the top 281 genetic variants that were most associated with old age served as a sort of constellation of genetic markers that were strongly associated with extreme old age.

“If you inherit just the right combination of variations of those genes, then that can have a very, very strong influence on the ability to get to a very old age,” he said. “It’s like the lottery. If you get one number or two numbers, that’s not a very rare event. But to get all seven numbers, or to get all genes in the right combinations, that’s very rare.”

The average human life expectancy has increased at a rate of three months per year since 1840, with no signs of slowing down, and aging researchers are now focusing on supercentenarians rather than centenarians. Studies have found a delay in onset or complete absence of age-related diseases, such as diabetes and Parkinson’s disease, in this group, even more so than in centenarians. Supercentenarians aren’t just living longer — they’re living healthier, too.

So what kind of genetic lottery does living a whole decade beyond 100 entail? Last year, Kim sequenced the whole genomes of 17 supercentenarians — the largest group yet for such an experiment — to tease out a possible genetic basis.

“Supercentenarians are something like 1 in 20 million people, and we had hoped that there would be some crazy mutation in there that would confer crazy-long lifespans on a person,” said Kim. “Now that we looked at 17 supercentenarians, all I can say is that if the genetic signatures were really simple, some of the tests we did would have found them.”

Constrained by their small sample size, Kim and his colleagues were unable to find any significant genetic markers for supercentenarians. Perls believes it would take 500 to 1000 genomes to truly unlock their secrets.

“Looking at the whole-genome sequence, which is a huge number of variables, there’s no way that 17 people are going to tell you anything,” he said.

Perls is the founding director of the New England Centenarian Study, which so far has enrolled 2,000 centenarians, 150 supercentenarians, and about 500 of their children who are expected to have inherited some of those favorable genetic variants. He has also created an online tool called the Living to 100 Life Expectancy Calculator to estimate lifespan based on day-to-day habits, family history, and demographics.

“I’ll have people in their mid-90s or early 100s say, ‘I took your test, and it told me I should be dead!’” Perls said. “I tell them they indicated a number of pretty bad health behaviors, and what that means is that they must have a remarkable set of genes.”