People age differently. Some sail into old age without a care in the world (or a chronic disease), while others start falling apart in middle age. As global populations get older, scientists are increasingly desperate to figure out why. Enter a new study presented at the European Society of Human Genetics conference, which suggests that the secret to a long, healthy life might be hiding in the genomes of entire families who just won't die.

Researchers from Leiden University Medical Center analyzed 212 groups of long-lived siblings and found four genomic regions that seemed to contain longevity genes. That narrowed the search from 20,000 genes to a more manageable 350. Further analysis revealed 12 rare protein-altering variants, including one in the CGAS gene, which is known to trigger inflammation when DNA is found where it shouldn't be (like during viral infections or cell damage).

In two long-lived families, carriers of this variant likely had only one active copy of the CGAS gene instead of two. That means their inflammatory response was tamped down - enough to still fight infections and repair damage, but not so much that it caused chronic inflammation and tissue wear. "It’s like having a mutted fire alarm," explains PhD student Pasquale Putter. "It still works, but it doesn’t go off at every little spark."

The researchers caution that this is early days. Completely disabling the CGAS pathway could leave you vulnerable to infections and cancer, while overactivating it leads to chronic inflammation. To test the mutation in a living creature, they plan to introduce it into killifish - the shortest-lived vertebrates, with a lifespan of three to nine months. "If the killifish live longer, we'll know we're onto something," says Putter. "If they just get really good at napping, that's also fine."

Professor Alexandre Reymond, who was not involved in the research, says the findings help zoom in on factors tied to longevity and "point to what maybe are key elements to extend the healthspan of all." In other words, if you want to live long, pick your parents wisely - and maybe get your CGAS gene checked.