It has long been known that exceptional longevity runs in families, leading scientists to suspect that genetics play a role in long life. This suspicion was recently confirmed by researchers, who identified 150 genetic variants - called single nucleotide polymorphisms - that were common among people who lived to be 100 or older and may have contributed to their healthy aging. Using this information, they were able to develop a system of genetic analysis by which they can predict - with 77 percent accuracy - whether someone will reach his 100th birthday.