To put the numbers into perspective, around two per cent of the American population carry two copies of the gene.
His findings were made public on an episode of his National Geographic documentary series, Limitless.
He explained to Vanity Fair how, “The show, which initially was an exploration of longevity and, of course, should be fun, became even more relevant and important for me, even more poignant than I ever thought.”
Learning about his own genetic predisposition put everything into perspective for Hemsworth, who shares daughter India, 10, and 8-year-old twin boys Sasha and Tristan with wife Elsa, 46.
“Doing an episode on death and facing your own mortality made me go, ‘Oh God, I’m not ready to go yet,’” he explained.
“I want to sit and be in this space with a greater sense of stillness and gratitude. And then you start talking about kids and family and going, ‘Oh my God, they’re getting older, they’re growing up and I keep slapping another movie on top of another movie.’ Before you know it, they’re 18 and they’ve moved out of the house, and I missed the window.”
WATCH: Limitless with Chris Hemsworth | Official Trailer. (Article continues after video)
That’s when Hemsworth made the decision to step back from his career for a time, surrounded by his loved ones.
“It really triggered something in me to want to take some time off,” the Thor actor conceded, after a huge few years creating blockbuster after blockbuster.
“Since we finished the show, I’ve been completing the things I was already contracted to do… I’m going home, and I’m going to have a good chunk of time off and just simplify. Be with the kids, be with my wife,” he told Vanity Fair.
While his genetic makeup certainly isn’t a death sentence – in fact, he may never develop Alzheimer’s – the action star is using the new information to better his quality of life, which starts at home in Byron Bay with his brood, his brothers Liam and Luke, and their extended family.
From soaking up the bushland and ocean frontage of their spectacular property to indulging in Elsa’s love of horse riding at their farm, every moment of Hemsworth’s hiatus will be spent doing what he loves and making memories to last a lifetime.
For more, pick up a copy of WHO. On sale now!