This is saying that DNA changes in a person’s body over time.
All I know is that my 6 pack abs cells have morphed into aluminum keg cells over time!
It's saying far more than that: it's saying that the DNA changes according to the needs and functions of specific cells.
What that means is, there is something that controls that change: a mechanism that alters DNA according to specific function. So what is that mechanism? How does it work, and from where does the relevant information come?
That's a very interesting question, which may be answered by the discoveries that have been accumulating about "meta information" within the DNA: information may be encoded "above" the single-gene level. My simple-minded analogy would be that the individual genes represent syllables, and the meta-data represents words of one or several syllables....
No wonder all those convicted murderers are getting released years later due to DNA not matching...