What is a gene?
A gene is a stretch of DNA that holds the instructions for making one specific product, usually a protein your body needs.
If your DNA is a cookbook, a gene is one recipe in it. A muscle cell and a brain cell carry the same cookbook. They just cook from different pages.
Why it matters for aging
Humans have roughly 20,000 genes that hold recipes for proteins. Having a gene isn't the same as using it: cells constantly switch genes on and off depending on what they need. Exercise, food, sleep and stress all change which genes are active, which is one reason lifestyle matters so much.
With age, gene switching gets less precise. Some genes that should be off turn on, and some that should be on fade. Research into resetting these patterns is one of the most exciting areas of longevity science.
A common myth
There's a "longevity gene", so if your parents lived long, you will too.
Hundreds of genes each have small effects on aging, and lifestyle plays a big role. Twin studies suggest genes explain roughly a quarter of the differences in how long people live, and some large family-tree studies suggest even less.
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Updated Nov 7, 2026 · All terms