well, genetic markers are added onto the underlying DNA, though not changing the actual structure ... but trying to dumb down a scientific discussion into layman language is pointless ...
@Shifty: a modern addition/interpretation would make it neo-Lamarckism ... however, there is still no conclusive research in the field as of yet ... but suffice it to say, if the elephant's trunk was a genetic change caused by the accumulation of a consistent action (reaching using the nose) consistently repeated over several generations, there is something to the idea that genetic changes -- however minute -- happen over the course of an organism's lifespan, and those changes are inherited ...
and another set of questions that need to be asked, which Mus was kind of alluding to, is how a "DNA test" is actually administered, what they look for when ascertaining the results, how the accuracy of the "test" can be measured, and what developments have happened in this field ...