Each week, OMRF Chief Medical Officer Dr. Judith James opens “Adam’s Journal” to answer a medical question from Adam Cohen, OMRF’s senior vice president & general counsel.
I know that our lifespans are determined by a combination of nature and nurture. But if you had to pick a number, just how much of a role do genes play in our longevity?
Dr. James Prescribes
Historically, scientists had estimated that genes account for a significant portion of your life expectancy, somewhere in the neighborhood of 15% to 40%. But in recent years, research suggests genes alone may play a much smaller part in how long we live.
Most notably, a 2018 study in the journal Genetics used data gathered from the genealogical website Ancestry to analyze 54 million family trees. In total, they looked at de-identified birth and death data from more than 400 million people born from the 19th century until the mid-20th century. (Most people born more recently are still alive.)
The scientists found that genes accounted for less than 7% of people’s lifespans.
The first clue that genes aren’t as important as once thought came when researchers compared wives and husbands to sisters and brothers. They found that spouses’ lifespans were more similar than those of siblings.
Because siblings have much more in common genetically than spouses, this suggests that a stronger influence on longevity comes from shared non-genetic factors like healthy (or unhealthy) diets, abstaining from tobacco (or not), access to healthcare, and activity levels.
Interestingly, there were also high correlations in lifespans between people and the families they married into. This once again underscores the importance of lifestyle in longevity, as the people we choose to spend our lives with often share significant behavioral traits with other members of their family. In other words, attitudes about alcohol use and food often run in families, as do income and education levels, which are also predictors of lifespan.
It’s worth noting that when it comes to the extremely long-lived, scientists have identified certain genes and genetic clusters that seem to predict exceptional longevity. For example, a study of centenarians in the journal Science reported identifying a set of genetic variants that predicts a lifespan of 100-plus years with 77% accuracy.
Still, 99.97% of Americans won’t reach the century mark. So, the best strategy is to focus on the factors we can control. They’ll likely play the lead role in determining how long – and, just as importantly, how well – we live.
Do you have a health query for Dr. James? Email firstname.lastname@example.org and your question may be answered in a future column!