How long you'll live

Does your family history decide how long you'll live?

By GyroscopeUpdated November 14, 20265 sources

Less than most people think. Lifespan is only weakly inherited. The classic twin study put the genetic share at about a quarter, and the largest family-tree study at under 10%. A parent’s heart disease at a young age is a real warning. A grandmother who lived to 95 helps less than you’d hope.

Why it feels like it’s all in the genes

Everyone knows a family where everyone reaches 95 and another where the men die in their 60s. It looks like fate. But families share a lot more than DNA. They share kitchens, smoking habits, money, neighborhoods and ideas about doctors. When long life runs in a family, it’s hard to tell which of those is doing the work.

The in-law surprise

In 2018 a team from Calico and Ancestry tested this with public family trees covering hundreds of millions of people born in the 1800s and early 1900s. Blood relatives’ lifespans were linked, as expected. But in-laws’ lifespans were linked almost as closely, and in-laws share no genes.

The reason is that people tend to marry people like themselves, in habits, wealth and health. Once the researchers allowed for that, the share of lifespan that’s genetic came out “well below 10%”. The classic Danish twin study, of 2,872 twin pairs born from 1870 to 1900, had put it at 0.26 for men and 0.23 for women, which is still a minority.

The simple version

Your genes are like the house you inherited. The foundation came from your parents, and a bad one makes some problems more likely. But whether the roof holds up in 30 years depends mostly on how it’s kept.

When family history does count

A parent’s early heart disease. In the Framingham Offspring Study, 2,302 adults with an average age of 44 were followed for 8 years. Those with a parent who had heart disease young (a father before 55 or a mother before 65) had about twice the risk of heart disease themselves, even after adjusting for their own blood pressure, cholesterol and other risks. Later-life heart disease in a parent predicted much less.

That’s useful, because much of that risk shows up in numbers you can measure and change, like blood pressure and the particles that carry cholesterol. See which blood tests matter most.

Very long-lived relatives. A 2019 study of 314,819 people in 20,360 families in Utah and the Netherlands found longevity passed down only when relatives reached the top 10% of survivors from their own birth year. With such relatives, people had up to 31% better survival. Relatives who reached an ordinary old age made no measurable difference.

How it compares with habits

In the big Harvard habits study, five habits at 50 meant about 14 more years for women and 12 for men than having none. Genes matter most at the far end. Survival to extreme ages clusters in families, which fits the Utah and Dutch finding that only relatives in the top tenth of their generation passed anything on.