Scientifically, hypothetically, or in plausible fiction, is there any possible fluke of the genetic code or something similar which could cause a person to stop aging?

A lot of T.V shows, movies, etc deal with the theme of immortality. Or, at least, stopping age progression for ridiculously long lifespans.

Is aging a part of the “programing” of our DNA? Is something in the genetic code telling our cells when to stop doing this or that, and its time to shut it down?

What if, once a person grew to be a certain age, simply stopped getting older physically. What could cause that?

No, I have no ambitions for immortality. But its common in sci fi, horror, and epic fiction. Most of the crap I write is pretty much just written for myself, but I wonder what could make this scientifically plausible.