It doesn't really degrade. The shortening of the telomers only seems to be relevant at really high age. What happens to the DNA is that some parts of it may be activated and deactivated by methylations and such (imagine as glueing something to the strands), and yes, this process is influenced by your environment. So while Lucas DNA-sequence would remain the same all those years, the pattern of deactivated and activated strangs would be different. In the tests you refer to only the sequence is tested, not the "modifications". But the modifications are extremely important as they decide which genes are decoded and therefore which proteins are produced. And proteins control most of what happens in the body.