The brothers and sisters of centenarians are more likely to survive to very old age, according to a study of family life histories.

The U.S. study included data from 444 people who lived to be 100 or more, and their siblings. The centenarians' data was compared to survival data for a representative sample of people born in 1900.

The data suggested sisters of centenarians had about half the risk of dying at any given age compared to the U.S. average. Brothers of centenarians also had low mortality rates, except as teens and early adults.

You may be more likely to live to 100 if your sibling has
You may be more likely to live to 100 if your sibling has

(Young males typically have higher mortality rates than other age groups.)

The lower mortality rates greatly enhanced the odds that siblings of centenarians would live that long themselves, the researchers said. Compared to the general population, the brothers were 17 times more likely to reach age 100, and sisters were eight times more likely to do so.

Dr.Thomas Perls, director of the New England Centenarian Study, John Wilmoth of the University of California, Berkeley, and their colleagues analyzed the data. Their study appears in Tuesday's issue of the Proceedings of the National Academy of Sciences.

In an earlier analysis of a smaller cluster of families, the researchers found that siblings of centenarians have a four times greater chance of living into their early 90s than the general population. Other studies have also found patterns of exceptional longevity running in families.

In 2001, Perls and his colleagues found a region on chromosome 4 that seems to help people live to be 100, but scientists haven't found the specific genes or how they work.

The finding "provides further evidence that centenarians and their relatives are a special group in that they appear to be more resistant to disease or they survive disease better throughout the life span," said Dr. Evan Hadley.

He is the associate director for geriatrics and clinical gerontology for the National Institute of Aging, which helped fund the study.