So the commonly cited example of "you replace all the cells in your body roughly every 7 years" is only sorta accurate; there's a few exceptions to that that make it a poor example of the Ship of Theseus. Some of your nerve cells (like, in your brain) don't actually get replaced very often, if at all. Women don't produce more ova over the course of their life, so until menopause, those are a static set of cells that aren't replaced over time.
You could argue that the component molecules in those cells are being replaced as natural processes occur, but it is not infeasible that a few of the component molecules in your body (like, say, the DNA in your nerve cells), could survive from the moment of birth/conception/whatever until the point where you die.