Question 10 of 24
How long did your grandparents tend to last?
The short answer
Twin and pedigree studies long put the heritability of human lifespan at roughly 20 to 30 per cent. A 2018 analysis of an enormous ancestry pedigree dataset found that once assortative mating was properly modelled — people tend to partner with others of similar longevity-related circumstances — the estimate collapsed to well under 10 per cent. Heritability is in any case a statement about variation across a population, not a percentage of your own lifespan that is already decided.
Pick one to continue — the dead don't get to skip homework.
Do 'good genes' actually exist?
💀 A grim little fact
Everyone wants to believe long life runs in the family. The science is spicier. Classic family-tree studies suggested the heritability of human lifespan is as low as ~7% — because couples tend to resemble each other (assortative mating), which fooled older estimates into over-crediting genes. A 2025 study pushed back, arguing that once you strip out random accidents, intrinsic heritability is closer to 50%.
Translation: genetics matter, but nobody's holding a golden ticket. Most of your lifespan is written by luck and lifestyle, not lineage.
🔮 Myth vs. Morty
Myth: "My gran smoked two packs a day and lived to 95, so I'm basically bulletproof." That's survivorship bias wearing a cardigan. You remember the one indestructible gran; you don't tally the neighbours who ran identical habits and left early. Gran won a lottery. Lotteries are, famously, not a retirement plan.
Sources: lifespan heritability studies (family pedigree ~7%; 2025 twin re-analysis ~50%) · Entertainment only — not medical advice.
Is longevity genetic? What the evidence shows
Last reviewed · compiled by the ExpireOnDate editorial team · not medically reviewed
What the research shows
In pedigrees covering 831.7 million historical individuals, mostly of European descent born 1800–1920, nominal sibling- and cousin-based heritability estimates for longevity fell between 20% and 30%, consistent with prior estimates of 15–30%.
historical individuals of largely European descent, born 1800–1920 · primarily United States · large-scale pedigree-based statistical genetics analysis · 2018 · Genetics
When the same data was modelled to account for assortative mating using sibling-in-law networks, the transferable heritability estimate fell to well below 10%, with a maximum under about 7%.
same pedigree population · primarily United States · structural equation modelling of sibling-in-law networks · 2018 · Genetics
A 2025 study using a different method reported heritability of intrinsic human lifespan at about 50% once certain confounders were addressed, showing how sensitive these estimates remain to method.
not specified · not specified · genetic analysis addressing confounding · 2025 · Science
What it does not show
Heritability is a population variance statistic tied to the population, era and environment studied. It says nothing about any individual's chances, and it does not mean some fixed share of your life is genetically pre-booked. Estimates swing widely depending on how assortative mating and shared family environment are handled, and historical Western pedigrees may not generalise anywhere else.
Every figure on this page describes a population, not a person. Associations measured across thousands of people cannot tell any individual how long they will live, and nothing here is medical advice. If something on this page concerns you, talk to a doctor rather than a comedy website.
References
- Estimates of the Heritability of Human Longevity Are Substantially Inflated due to Assortative Mating. Genetics (2018). primary source; accessed 2026-08-15.
- Heritability of intrinsic human life span is about 50% when confounding factors are addressed. Science (2025). primary source; accessed 2026-08-15.
- A meta-analysis of genome-wide association studies identifies multiple longevity genes. Nature Communications (2019). secondary reporting; accessed 2026-08-15.
Spotted an error or a better source? Tell us — corrections are logged and the review date updated.