Haha, sure you can't change your DNA. You need to research before you post my friend.

Here are some examples of DNA changing.
1: The virus HIV infects cells and alters their DNA by incorporating their RNA into our DNA by an enzyme called reverse transcriptase. [Link]
2: Cancer starts by the DNA changing and the cell forgetting its function. [Link]
3: Designer babies are 'designed' by changing the egg/sperms DNA. [Link]
4: Gene therapy works by using an GENETICALLY altered virus to change the DNA of cells. [Link]
5: Ever heard of GM foods? Thats genetically modified. Which means changing the genetics of the plant. [Link]