Is your lifespan determined by your genes? An intriguing new study of centenarians — those who live 100 years or longer — suggests the answer may be yes. What’s more, the findings suggest genetics are a key factor in how active and alert some people remain well into very old age.

The study, by scientists at Stanford University and the University of Bologna, may help explain the genetic basis for extreme longevity. The findings, published by Kristen Fortney and colleagues in the Public Library of Science journal PLOS Genetics, indicate certain genetic traits may offer protection against some age-related conditions that can cut life short — such as kidney disease, cardiovascular problems, and Alzheimer’s.

To find the "longevity genes," the researchers examined genetic links to 14 diseases to identify those associated with longer life. The scientists identified five specific genetic features known to be involved in various health conditions.

“We have shown that one of the genetic mechanisms for extreme longevity involves the avoidance of certain [genetic structures] that predispose to common diseases, including coronary artery disease, Alzheimer’s disease, high cholesterol and chronic kidney disease,” the researchers write.

They note that previous studies have shown that centenarians have health and diet habits similar to the average person, suggesting that factors in their genetic make-up could contribute to longevity.

But, until now, genetic studies have identified only a single gene (APOE, known to be involved in Alzheimer's disease) that was different in centenarians versus those who live shorter lives.

The risk of developing cancer, heart disease, Alzheimer’s, and nearly all diseases increases with age, so understanding genetic factors involved in those processes could help people live longer and healthier lives, the researchers said.